CN107274725B - A kind of mobile augmented reality type card identification method based on mirror-reflection - Google Patents
A kind of mobile augmented reality type card identification method based on mirror-reflection Download PDFInfo
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- CN107274725B CN107274725B CN201710382651.5A CN201710382651A CN107274725B CN 107274725 B CN107274725 B CN 107274725B CN 201710382651 A CN201710382651 A CN 201710382651A CN 107274725 B CN107274725 B CN 107274725B
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- 238000000034 method Methods 0.000 title claims abstract description 16
- 230000003190 augmentative effect Effects 0.000 title claims abstract description 12
- 238000013461 design Methods 0.000 claims abstract description 52
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B5/00—Electrically-operated educational appliances
- G09B5/02—Electrically-operated educational appliances with visual presentation of the material to be studied, e.g. using film strip
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B17/00—Details of cameras or camera bodies; Accessories therefor
- G03B17/02—Bodies
- G03B17/17—Bodies with reflectors arranged in beam forming the photographic image, e.g. for reducing dimensions of camera
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T11/00—2D [Two Dimensional] image generation
- G06T11/60—Editing figures and text; Combining figures or text
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T19/00—Manipulating 3D models or images for computer graphics
- G06T19/006—Mixed reality
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T3/00—Geometric image transformations in the plane of the image
- G06T3/02—Affine transformations
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Abstract
The invention belongs to mobile augmented reality technical fields, provide a kind of mobile augmented reality type card identification method based on mirror-reflection, comprising: (1) mirror-reflection designs, including the design of pedestal, mirror housings, reflective mirror.(2) design of picture is registered.(3) card design of facing moving terminal adaptation.(4) ortho-rectification of image is acquired.The present invention passes through the reflector apparatus specially designed, in conjunction with image rectification technology, the card of mobile terminal bottom front is properly mapped on screen, reflector apparatus solves the problems, such as to need handheld device to remove scanning card, child restraint both hands in traditional AR identification.Meanwhile the ortho-rectification for acquiring image effectively overcomes in tional identification because front camera acquired image deforms the problem for causing recognition efficiency low.
Description
Technical field
The invention belongs to mobile augmented reality (Augmented Reality, AR) technical fields, more particularly, to one
Mobile augmented reality type card identification method of the kind based on mirror-reflection.
Background technique
Augmented reality be field of virtual reality development a branch, while be also computer vision, computer graphics,
Cross one another, the brand-new research field of the multiple technologies such as multimedia, human-computer interaction is, it can be achieved that real world and virtual world
Seamless connection.This feature is combined using actual situation, realizes the interaction inside and outside mobile terminal screen, the manipulative ability of training children；
It is more able to ascend children from the form of expression to the interest of things, detected in a manner of interaction, study deeper content.With
The promotion of mobile terminal computing capability, the integrated use of various sensing modules, the combination of AR technology and mobile technology realize
The miniaturization and portability of AR can meet the needs of people are for interactivity, instantaneity, personalization.
Preschool education card is that the classical education resource of one kind can assign its more digital content by AR technology,
Completely new Interactive Experience mode can more effectively reader.It has currently emerged in large numbers a series of planes and has published class AR product, such as taught
Educate card, draw sheet and teaching material etc..Combining with education card is wherein more typical one kind children's AR product, relative to traditional
Educate card, AR educates card by intelligent terminal, simulates scene true to nature, meet make, with soon, listened with ear, use
The diversification education ideas that brain is thought.But there is also following defects for this kind of product: needing children's handheld device to sweep when (1) using
It retouches, constrains children's both hands to a certain extent, the manipulative ability of children can not be tempered；(2) the education card for being used to identify needs
Want more characteristic point, it is desirable that color complexity is higher；(3) mobile terminal video camera acquired image is not corrected.
These defects limit the development and application of AR education card, it is necessary to explore new education card identification method.
Summary of the invention
Aiming at the above defects or improvement requirements of the prior art, the mobile increasing based on mirror-reflection that the present invention provides a kind of
Strong reality type card identification method, this method is simple, convenient, efficiently solves in traditional AR identification and handheld device is needed to go
The problem of scanning card, child restraint both hands.
The purpose of the present invention is what is realized by following technical measures.
A kind of mobile augmented reality type card identification method based on mirror-reflection, includes the following steps:
(1) mirror-reflection designs, and mobile terminal is placed on pedestal, places one above mobile terminal front camera
Block reflective mirror enables front camera to collect the figure of identification region in front of mobile terminal base using mirror reflection principle
Picture, the shape, size of reflective mirror, placed angle adjust the size of identification region in front of pedestal in turn through reasonable settings；
(2) registration picture design, be based on " frame flag " design principle, select have black and white sawtooth image edge as
Characteristic signature, other regions other than picture black and white sawtooth are superimposed corresponding learning Content design information, AR are facilitated to know
It does not use；
(3) card design of facing moving terminal adaptation, finds most suitable identification region, and according to the big of identification region
The small optimal card dimensions of design；
(4) ortho-rectification for acquiring image, with image ortho-rectification technology to the collected figure of mobile terminal video camera
As being corrected, former identification image is obtained.
In the above-mentioned technical solutions, the design of mirror-reflection described in step (1) specifically comprises the following steps:
The production of (1-1) mirror housings, mirror housings are for making reflective mirror be fixed on mobile terminal front camera
Top；The shell includes the shell of the unclosed rectangular parallelepiped structure in bottom, and according to the design of reflective mirror, shell size is set
For 5cm*5cm*6cm, one end of shell is provided with card slot identical with mobile terminal thickness, before being fixed on mirror housings
Before setting camera, face is conformed to as reflective mirror in the inclined surface that enclosure interior is equipped with certain angle, for being embedded in reflective mirror, makes anti-
Light microscopic is fixed on above mobile terminal front camera, and the top of reflective mirror and the top of mobile terminal are consistent, and reflective mirror conforms to
Angle between face and mobile terminal is 30 °~50 °；
The production of (1-2) mobile terminal base, mobile terminal base for standing mobile terminal flat at an angle
On face, facilitate projection of the content of identification region in front of pedestal in front camera；The pedestal is by whole for holding movable
The support panel and adjusting panel at end form, and the support panel and adjusting panel are hinged in upper end, by adjusting supporting surface
Angle between plate and adjusting panel, and then adjust the angle of mobile terminal and horizontal plane；
The production of (1-3) reflective mirror, the effect of reflective mirror are that front camera is enable to collect cog region in front of pedestal
Area image, the reflective mirror are rectangle；The long l of reflective mirror1Distance d with wide w, front camera apart from mobile terminal top1With
And the relationship between the view frustums angle [alpha] of front camera is as follows:
In the above-mentioned technical solutions, the design of registration picture described in step (2) specifically comprises the following steps:
The method that (2-1) is based on " frame flag " selects the image edge with black and white sawtooth as characteristic signature；
(2-2) adds learning Content design information, soft in image procossing according to the requirement of learning Content and identification figure production
Design and editing picture in part, the ratio of width to height 1:1, pixel placement 2048*2048, file memory format are * .jpg, to improve
The design of the precision of identification, picture need to be handled as follows:
The design of (2-2-1) picture internal color, the color of black and white sawtooth internal image are obvious with sawtooth color contrast；
The design of (2-2-2) picture exterior color, the color of black and white sawtooth outer boundary will compare bright with sawtooth black border
It is aobvious.
In the above-mentioned technical solutions, the card design of the adaptation of facing moving terminal described in step (3) specifically includes as follows
Step:
(3-1) determines the tilt angle of mobile terminal, the angle of the tilt angle, that is, mobile terminal and desktop, it is known that mobile
A length of l of terminal itself2, terminal vertex is h perpendicular to the height of desktop, calculates its tilt angle using trigonometric function formula
θ, calculation formula are as follows:
Sin θ=h/l2
(3-2) finds maximized projected area, throwing of the angle to front camera of mobile terminal and reflective mirror, desktop
It penetrates region all to have an impact, if the angle of reflective mirror and mobile terminal is smaller, front camera acquisition zone can be shown in reflective mirror
The content in domain is fewer, and the view frustums of front camera cut by reflective mirror it is smaller；Conversely, angle is bigger, then reflective mirror
In can show that the content of front camera pickup area is more, while front camera view frustums be retained it is more, meanwhile,
Otherwise angle is shot no more than the upper limit of front camera view frustums less than the content in reflective mirror；
It is as follows specifically to solve maximized projected area:
(3-2-1) determines mobile terminal front camera view frustums bound, and mobile terminal is inclined in table at a certain angle
On face: EQW is desktop, and EOO' is mobile terminal, and wherein O point is front camera position, and O' point is top at the top of terminal
The distance of O' point to desktop E point be it is fixed, if EO'=d2；The distance of top O' point to front camera O point be it is fixed,
If OO'=d3, after placing mobile terminal, ∠ O'EW is also determined, and is set as ∠ C；OD is preposition camera shooting perpendicular to EOO', OD
The z positive axis of head；OO' is the y positive axis of front camera；OA and OC constitutes the bound of front camera view frustums；
(3-2-2) obtains the intersection point of mirror surface and front camera view frustums, and O'HMW is plane where reflective mirror, according to need
By on the upper limit OA of the E point reflection on desktop to front camera view frustums, the picture of such EOO' on mobile terminals is then
It is completely invisible in front camera, according to this demand, obtain AO'=EO'=l2, it is possible thereby to determine A on OA line
The position of point, then connects EA, then make mirror surface O'HMW perpendicular to EA, then mirror surface and front camera view frustums or more can be obtained
The intersection point H point of limit and the intersection point W of M point and mirror surface and desktop, and what mirror surface really played reflex is exactly mono- section of HM；
(3-2-3) finds the width of projected area, the point Q on desktop is found, so that Q point is just fallen in after mirror-reflection
On the lower limit P point of front camera view frustums, to reach this purpose, connection AW and OC intersects at P point, and it is vertical to make PQ for P point excessively
Q point can be obtained in mirror surface, in this way, the EQ on desktop entirely falls within the view of front camera just through mirror reflection at AP
It is photographed, and is displayed on the screen in cone, EQ is the width of projected area；
(3-2-4) finds the length of projected area, and the incident light at front camera wide-angle edge is after reflective mirror reflects
Most marginal two reflection lights are made the dotted line perpendicular to desktop C, E two o'clock by reflection light, and connection CD and EF can get two
Line, in this way, the DF on desktop is the length of projected area；
(3-3) by projected area determine carrying card maximum quantity and most suitable card dimensions；
(3-4) card material design, in order to improve recognition speed and stability, it is ensured that the real-time presentation of cartoon scene is adopted
With the card of frosted material.
Technical effect of the invention is embodied in:
It is in conjunction with image rectification technology, the card before mobile terminal screen is correct by the mirror apparatus specially designed
It is mapped on screen.The ortho-rectification of acquisition image overcomes in tional identification because the deformation of front camera acquired image is led
The problem for causing recognition efficiency low；Mirror apparatus, which solves, needs handheld device to remove scanning card, constraint youngster in traditional AR identification
The problem of virgin both hands.
Detailed description of the invention
Fig. 1 is the schematic illustration of the method for the present invention.
Fig. 2 is the structural schematic diagram of mirror housings in the present invention, is become apparent from here for by its structure representation, and selection is anti-
The visual angle performance of light microscopic outer casing bottom upward, and it is opposite with visual angle when mirror housings normal use.
Fig. 3 is the structural schematic diagram of pedestal in the present invention.
Fig. 4 is the picture schematic diagram that characteristic signature is had in the present invention.
Fig. 5 is the registration picture schematic diagram that design information is superimposed in the present invention, herein only schematic diagram, and is actually being answered
It should be obvious with sawtooth color contrast with the color of middle black and white sawtooth internal image.
Fig. 6 is identification region width projection mapping schematic diagram in the present invention.
Fig. 7 is identification region length projection mapping schematic diagram in the present invention.
Fig. 8 is perspective projection conversion parallel projection schematic diagram.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with attached drawing and case study on implementation,
The present invention will be described in further detail.It should be appreciated that specific implementation case described herein is only used to explain this hair
It is bright, it is not intended to limit the present invention.In addition, technical characteristic involved in the various embodiments of the present invention described below
It can be combined with each other as long as they do not conflict with each other.
As shown in Figure 1, the embodiment of the present invention provides a kind of mobile augmented reality type card recognition side based on mirror-reflection
Method, it is characterised in that this method comprises the following steps:
(1) design of mirror-reflection
The pedestal erect including reflective mirror design, mirror housings design, support mobile terminal designs three parts.Reflective mirror
Effect be that mobile terminal front camera is enable to collect identification region image in front of pedestal.The size and shape of reflective mirror
It is determined according to the top of the view frustums angular dimension and front camera of mobile terminal front camera and mobile terminal distance.Instead
The placed angle of light microscopic shell control reflective mirror realizes that identification region is of moderate size in front of pedestal.Pedestal design mainly control moves
The tilt angle of dynamic terminal.
The mirror-reflection design specifically comprises the following steps:
The production of (1-1) mirror housings, mirror housings are for making reflective mirror be fixed on mobile terminal front camera
Top；As shown in Fig. 2, the shell includes the shell 1 of the unclosed rectangular parallelepiped structure in bottom, it, will according to the design of reflective mirror
1 size of shell is set as 5cm*5cm*6cm, and one end of shell 1 is provided with card slot 2 identical with mobile terminal thickness, and being used for will be anti-
Before light microscopic shell is fixed on front camera, face 3 is conformed to as reflective mirror in the inclined surface inside shell 1 equipped with certain angle,
For being embedded in reflective mirror 4, it is fixed on reflective mirror 4 above mobile terminal front camera, in order to make the cone of front camera
Body is not blocked by reflective mirror, and the top of reflective mirror is consistent with the top of mobile terminal, to keep reflective mirror and front camera
Between have certain distance, the top of reflective mirror and the top of mobile terminal are consistent, and reflective mirror conforms between face and mobile terminal
Angle is 30 °~50 °.
The production of (1-2) mobile terminal base, mobile terminal base for standing mobile terminal flat at an angle
On face, facilitate projection of the content of identification region in front of pedestal in front camera；As shown in figure 3, the pedestal is by being used for
The support panel 5 and adjusting panel 6 of holding movable terminal form, and the support panel 5 and adjusting panel 6 are hinged in upper end,
By adjusting the angle between support panel 5 and adjusting panel 6, and then adjust the angle of mobile terminal and horizontal plane；Pedestal is wanted
With certain stability, mobile terminal can be supported for a long time.
The production of (1-3) reflective mirror, the effect of reflective mirror are that front camera is enable to collect cog region in front of pedestal
Area image, the reflective mirror are rectangle；The long l of reflective mirror1Distance d with wide w, front camera apart from mobile terminal top1With
And the relationship between the view frustums angle [alpha] of front camera is as follows:
(2) design of picture is registered
Based on the design principle of " frame flag ", select the image edge with black and white sawtooth as characteristic signature, such as
Shown in Fig. 4, it is superimposed corresponding learning Content design information by other regions other than picture black and white sawtooth, AR is facilitated to identify
It uses.According to the requirement of learning Content and identification figure production, in image processing software (such as Photoshop), design and editor
The ratio of width to height of picture is designed as 1:1 by picture, and saves as * .jpg format, as shown in Figure 5.It is incited somebody to action in use, moving AR and applying
Analyzed according to the image information of acquisition, with identification library in chartered picture matched, if successful match, in screen
On will appear cartoon scene corresponding with image content.
(3) card design of facing moving terminal adaptation, finds most suitable identification region, and according to the big of identification region
The small optimal card dimensions of design.
Design card dimensions, it is necessary first to obtain the tilt angle of terminal, next obtains maximized projected area, leads to
It crosses projected area and calculates the maximum quantity for carrying card and most suitable card dimensions, the material of last further design card
Matter.What maximized projected area was codetermined by both tilt angles of reflective mirror and pedestal, if reflective mirror and mobile terminal
Angle it is smaller, then can show that the content of front camera pickup area is fewer in reflective mirror, and the cone of front camera
Body is cut smaller by reflective mirror；Conversely, angle is bigger, then it can show that the content of front camera pickup area is got in reflective mirror
It is more, at the same front camera view frustums be retained it is more.Certainly, angle is upper no more than front camera view frustums
Limit, otherwise shoots less than the content in reflective mirror.
The card design of the facing moving terminal adaptation specifically comprises the following steps:
(3-1) determines the tilt angle of mobile terminal, in order to enhance the experience sense of user, facilitate user observation, operate with
And obtain and maximize cog region, mobile terminal need to be inclined in desktop at a certain angle, and tilt angle can be adjusted freely.It is mobile whole
Tilt angle, that is, the mobile terminal at end and the angle of desktop, it is known that a length of l of mobile terminal itself2, terminal vertex is perpendicular to table
The height in face is h, calculates its tilt angle theta, calculation formula using trigonometric function formula are as follows:
Sin θ=h/l2
(3-2) finds maximized projected area, throwing of the angle to front camera of mobile terminal and reflective mirror, desktop
It penetrates region all to have an impact, if the angle of reflective mirror and mobile terminal is smaller, front camera acquisition zone can be shown in reflective mirror
The content in domain is fewer, and the view frustums of front camera cut by reflective mirror it is smaller；Conversely, angle is bigger, then reflective mirror
In can show that the content of front camera pickup area is more, while front camera view frustums be retained it is more, meanwhile,
Otherwise angle is shot no more than the upper limit of front camera view frustums less than the content in reflective mirror；
It is as follows specifically to solve maximized projected area, as shown in Figure 6,7:
(3-2-1) determines mobile terminal front camera view frustums bound, and mobile terminal is inclined in table at a certain angle
On face: EQW is desktop, and EOO' is mobile terminal, and wherein O point is front camera position, and O' point is top at the top of terminal
The distance of O' point to desktop E point be it is fixed, if EO'=d2；The distance of top O' point to front camera O point be it is fixed,
If OO'=d3, after placing mobile terminal, ∠ O'EW is also determined, and is set as ∠ C；OD is preposition camera shooting perpendicular to EOO', OD
The z positive axis of head；OO' is the y positive axis of front camera；OA and OC constitutes the bound of front camera view frustums；
(3-2-2) obtains the intersection point of mirror surface and front camera view frustums, and O'HMW is plane where reflective mirror, according to need
By on the upper limit OA of the E point reflection on desktop to front camera view frustums, the picture of such EOO' on mobile terminals is then
Completely invisible in front camera (because EOO' has been reflected on AO' line, having exceeded the range of view frustums), according to this
Demand obtains AO'=EO'=l2, it is possible thereby to determine the position of A point on OA line, EA is then connected, then make mirror surface O'HMW
Perpendicular to EA, then the intersection point H point and M point and mirror surface and desktop of mirror surface and front camera view frustums bound can be obtained
Intersection point W, and what mirror surface really played reflex is exactly mono- section of HM；
(3-2-3) finds the width of projected area, the point Q on desktop is found, so that Q point is just fallen in after mirror-reflection
On the lower limit P point of front camera view frustums, to reach this purpose, connection AW and OC intersects at P point, and it is vertical to make PQ for P point excessively
Q point can be obtained in mirror surface, in this way, the EQ on desktop entirely falls within the view of front camera just through mirror reflection at AP
It is photographed, and is displayed on the screen in cone, EQ is the width of projected area；
(3-2-4) finds the length of projected area, and the incident light at front camera wide-angle edge is after reflective mirror reflects
Most marginal two reflection lights are made the dotted line perpendicular to desktop C, E two o'clock by reflection light, and connection CD and EF can get two
Line, in this way, the DF on desktop is the length of projected area；
(3-3) by projected area determine carrying card maximum quantity and most suitable card dimensions；Wherein, card
The product of size and the quantity of carrying card should be less than projected area size；The area of projected area
The length and width of projected area is obtained by step (3-1), (3-2), so that projected area be calculated, is projected
The length in region determines the entire length of card, and the width of projected area determines the overall width of card.
Assuming that carrying number of cards is n, n is integer, and the area of projected area is S, and the area of identification card is set as S1,
Then:
N=S/S1
(3-4) card material design, in order to improve recognition speed and stability, it is ensured that the real-time presentation of cartoon scene.It moves
The identification picture of dynamic AR application need to meet certain requirement in printing, to facilitate front camera to carry out the spy of image feature value
It surveys and extracts.It is required that as follows: the picture of printing will guarantee glossiness.If picture smoother and glossy, for unrestrained anti-
It is smaller to penetrate possible influence under light conditions；But the case where if it is certain angle spotlight is had, then the light of card face
Pool may reflect a large amount of light, to influence the identification susceptibility of card.Using the card of frosted material in the present embodiment
Piece.
(4) ortho-rectification is carried out to the image that deformation occurs by perspective plane principle, it will be due to shooting angle and plane
The perspective projection for having certain angle to be formed is converted into parallel projection.
The principle of the ortho-rectification is as follows:
The basic principle of (4-1) perspective variation.Some viewpoint in z-axis, obtains the plane vertical with this axis in selection space
Perspective projection formula.Being located at viewpoint in z-axis is E (0,0, ze), certain point is P (x in spacep, yp, zp), then available view
The linear equation of line EP are as follows:
Parameter when this straight line and picture z=0 intersect is t=-ze/(zp-ze), parameter t is substituted into above formula and handle
Transform is applied to three coordinates, and due to any point that P is space, is write out with homogeneous coordinates, obtain expression formula are as follows:
It can thus be concluded that perspective transformation matrix of the viewpoint in z-axis.Similarly, viewpoint is obtained in the transformation matrix of x and y-axis, is divided
Not are as follows:
(4-2) perspective projection is converted into parallel projection.In order to further illustrate perspective transform PzThe case where object changes afterwards,
It is introduced by taking the perspective transform situation of a parameter straight line as an example, wherein c is slope:
It can be obtained in conjunction with the perspective transformation matrices of viewpoint in above-mentioned z-axis:
When straight line is to when infinite extension, have:
As shown in figure 8, the straight line AB parallel with z-axis, through PzBecome A ' B ' after transformation, it be in through the extended line of AB and
The intersection point G of picture and end point F (0,0 ,-Ze) straight line on.Positive throwing of the straight line A ' B ' (space object B2) on picture
Shadow A " B " is exactly perspective projection of the straight line AB (space object B1) on picture, and remains the corresponding relationship of depth direction.
The content being not described in detail in this specification belongs to the prior art well known to those skilled in the art.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (2)
1. a kind of mobile augmented reality type card identification method based on mirror-reflection, it is characterised in that this method includes following step
It is rapid:
(1) mirror-reflection designs, and mobile terminal is placed on pedestal, and one piece is placed above mobile terminal front camera instead
Light microscopic enables front camera to collect the image of identification region in front of mobile terminal base using mirror reflection principle,
The shape, size of reflective mirror, placed angle and then the size for adjusting identification region in front of pedestal through reasonable settings；
The mirror-reflection design specifically comprises the following steps:
The production of (1-1) mirror housings, mirror housings are for being fixed on reflective mirror above mobile terminal front camera；
The shell includes the shell of the unclosed rectangular parallelepiped structure in bottom, and according to the design of reflective mirror, shell size is set as
5cm*5cm*6cm, one end of shell are provided with card slot identical with mobile terminal thickness, preposition for being fixed on mirror housings
Before camera, face is conformed to as reflective mirror in the inclined surface that enclosure interior is equipped with certain angle, for being embedded in reflective mirror, makes reflective
Mirror is fixed on above mobile terminal front camera, and the top of reflective mirror and the top of mobile terminal are consistent, and reflective mirror conforms to face
Angle between mobile terminal is 30 °~50 °；
The production of (1-2) mobile terminal base, mobile terminal base are used to stand mobile terminal at an angle in the plane,
Facilitate projection of the content of identification region in front of pedestal in front camera；The pedestal is by the branch for holding movable terminal
Panel and adjusting panel composition are supportted, the support panel and adjusting panel are hinged in upper end, by adjusting support panel and tune
Angle between nodal section plate, and then adjust the angle of mobile terminal and horizontal plane；
The production of (1-3) reflective mirror, the effect of reflective mirror are that front camera is enable to collect identification region figure in front of pedestal
Picture, the reflective mirror are rectangle；The long l of reflective mirror1Distance d with wide w, front camera apart from mobile terminal top1And it is preceding
The relationship set between the view frustums angle [alpha] of camera is as follows:
(2) registration picture design, is based on the design principle of " frame flag ", selects the image edge with black and white sawtooth as feature
Distinguishing mark, other regions other than picture black and white sawtooth are superimposed corresponding learning Content design information, and AR identification is facilitated to make
With；
(3) card design of facing moving terminal adaptation, finds most suitable identification region, and set according to the size of identification region
Count optimal card dimensions；
The card design of the facing moving terminal adaptation specifically comprises the following steps:
(3-1) determines the tilt angle of mobile terminal, the angle of the tilt angle, that is, mobile terminal and desktop, it is known that mobile terminal
The a length of l of itself2, terminal vertex is h perpendicular to the height of desktop, calculates its tilt angle theta using trigonometric function formula, counts
Calculate formula are as follows:
Sin θ=h/l2
(3-2) finds maximized projected area, mobile terminal and reflective mirror, desktop angle to the projection area of front camera
Domain all has an impact, if the angle of reflective mirror and mobile terminal is smaller, front camera pickup area can be shown in reflective mirror
Content is fewer, and the view frustums of front camera cut by reflective mirror it is smaller；Conversely, angle is bigger, then energy in reflective mirror
Show front camera pickup area content it is more, while front camera view frustums be retained it is more, meanwhile, angle
No more than the upper limit of front camera view frustums, otherwise shoot less than the content in reflective mirror；
It is as follows specifically to solve maximized projected area:
(3-2-1) determines mobile terminal front camera view frustums bound, and mobile terminal is inclined on desktop at a certain angle:
EQW is desktop, and EOO' is mobile terminal, and wherein O point is front camera position, and O' point is O' point in top at the top of terminal
Distance to desktop E point be it is fixed, if EO'=d2；The distance of top O' point to front camera O point be it is fixed, if OO'
=d3, after placing mobile terminal, ∠ O'EW is also determined, and is set as ∠ C；OD is the z of front camera perpendicular to EOO', OD
Positive axis；OO' is the y positive axis of front camera；OA and OC constitutes the bound of front camera view frustums；
(3-2-2) obtains the intersection point of mirror surface and front camera view frustums, and O'HMW is plane where reflective mirror, as needed will
On E point reflection to the upper limit OA of front camera view frustums on desktop, the picture of such EOO' on mobile terminals is then preceding
It sets in camera and does not see completely, according to this demand, obtain AO'=EO'=l2, it is possible thereby to determine A point on OA line
Then position connects EA, then make mirror surface O'HMW perpendicular to EA, then mirror surface and front camera view frustums bound can be obtained
The intersection point W of intersection point H point and M point and mirror surface and desktop, and what mirror surface really played reflex is exactly mono- section of HM；
(3-2-3) find projected area width, find the point Q on desktop so that Q point just fallen in after mirror-reflection it is preposition
On the lower limit P point of camera view frustums, to reach this purpose, connection AW and OC intersects at P point, crosses P point and makees PQ perpendicular to mirror
Q point can be obtained in face, in this way, the EQ on desktop entirely falls within the view frustums of front camera just through mirror reflection at AP
It is inside photographed, and is displayed on the screen, EQ is the width of projected area；
(3-2-4) finds the length of projected area, reflection of the incident light at front camera wide-angle edge after reflective mirror reflects
Most marginal two reflection lights are made the dotted line perpendicular to desktop C, E two o'clock by light, and connection CD and EF can get two lines,
In this way, the DF on desktop is the length of projected area；
(3-3) calculates the maximum quantity for carrying card and most suitable card dimensions by projected area；
(3-4) card material design, in order to improve recognition speed and stability, it is ensured that the real-time presentation of cartoon scene, using mill
The card of sand material matter；
(4) acquire image ortho-rectification, with image ortho-rectification technology to mobile terminal video camera acquired image into
Row correction, is corrected the image that deformation occurs by perspective plane principle, will have a clamp due to shooting angle and plane
The perspective projection that angle is formed is converted into parallel projection, obtains former identification image.
2. the mobile augmented reality type card identification method according to claim 1 based on mirror-reflection, it is characterised in that
The design of registration picture described in step (2) specifically comprises the following steps:
The method that (2-1) is based on " frame flag " selects the image edge with black and white sawtooth as characteristic signature；
(2-2) adds learning Content design information, according to the requirement of learning Content and identification figure production, in image processing software
Design and editing picture, the ratio of width to height 1:1, pixel placement 2048*2048, file memory format are * .jpg, to improve identification
Precision, the design of picture need to be handled as follows:
The design of (2-2-1) picture internal color, the color of black and white sawtooth internal image are obvious with sawtooth color contrast；
The design of (2-2-2) picture exterior color, the color of black and white sawtooth outer boundary will compare obvious with sawtooth black border.
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