JP3411940B2 - How to create a two-dimensional digital mosaic photo map - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a digital photo map
It relates to a method of creating a dimension.

[0002]

2. Description of the Related Art In recent years, three-dimensional measurement is performed based on image data obtained from artificial satellites or aircraft, and three-dimensional measurement is performed based on this data, and terrain correction is performed using this data. A three-dimensional image processing technique has been developed for creating an image, and for creating an image (bird's-eye image) whose viewpoint is freely changed as needed.

A method of obtaining three-dimensional numerical image data from this type of image data is a digital terrain model (Digital Terrai).
n Model), which is known as a method for obtaining a so-called DTM. Currently, as a method for creating a DTM, a method using a topographic map, a method using an analytical plotting machine, or a method for performing a full-automatic measurement using a general-purpose computer. Etc.

The present applicant has also developed a method for obtaining three-dimensional numerical data from stereo image data as a three-dimensional image processing technique of this type, and has filed a patent application as Japanese Patent Application No. 1-308038. Japanese Patent Laid-Open No. 3-167678 discloses this method.

[0005]

However, since such an orthophoto creation method cannot be created without three-dimensional measurement, the cost is high for customers who do not need DTM (corresponding to level ground) and an order is received. There were many cases where it could not be reached. In addition, when hearing how to use the map itself from various customers from the perspective of using 3D data,
Most of them capture the map with a pictorial sense of looking at the two-dimensional positional relationship, and there are many things such as correcting the secular change of the place where the map already exists. In that case, an inexpensive two-dimensional analysis method. As a result, it was found that even if an orthophoto is created, it may be used sufficiently.

However, in the past, as for the technique capable of performing the two-dimensional mapping and the photographic mapping at a low cost, the fact that it can be put into practical use has not yet been developed, which is sufficient for the customer's request. There was nothing that could be answered.

An object of the present invention is to provide a method for inexpensively creating a two-dimensional photographic map in view of the above conventional technique.

[0008]

A method for two-dimensionally creating a digital mosaic photo map according to the present invention collects a map and a photo around a mosaic creation area, and outputs image data of the map and the photo from analog data. It is converted into digital data and stored as a map image file and a photographic image file, respectively, the map and the photographic image are displayed using the digital image data of the map image file and the photographic image file, and the displayed image is displayed. Decide the outline of polygon division by using it, display the decided polygons on the map image, and enlarge and reduce the map image and the photographic image displayed on the screen while supporting the polygon elements on the photographic image. The coordinates of the points on the image are measured, and the coordinates of the measured polygon element points are stored as a parameter file. Has been recorded in the file, the map image,
The polygon element points are finally determined by performing a low-order transformation on the corresponding polygons in the photographic image and checking the correspondence of the polygon element points based on the calculated residuals. A coefficient file for geometrically correcting polygons is obtained, a coefficient file for each polygon is created and stored, and a mosaic image creation table corresponding to the scale of the map is prepared. If it is determined that a certain point is inside a certain polygon, a photo image file and coefficient file corresponding to that polygon are called, and this point is determined using the coefficient corresponding to this polygon. The coordinate values of the corresponding points on the photo image are obtained by converting the coordinates on the table of The color information of the target, characterized by creating a digital photographic mosaic map to create a digital mosaic image by repeating such processing for all points on the table. Therefore, the method of the present invention is effective in areas where there is already a map.

According to a preferred embodiment of the present invention,
The aforementioned low-order transformation is performed by Helmert transformation or affine transformation, and the aforementioned geometric correction is performed by affine transformation or pseudo-affine transformation.

[0010]

The present invention will now be described in more detail with reference to the accompanying drawings.

FIG. 1 schematically shows the configuration of a system for carrying out a method for two-dimensionally creating a digital mosaic photographic map according to the present invention. This system comprises a computer 10 storing a digital mosaic application program 13 according to the present invention. The computer 10 has a keyboard 11 for inputting various data, commands, etc., and a character, an image, etc. for display. And a display (CRT) 12. further,
This system is attached to the computer 10, and has a hard disk 21 for image storage, a scanner 22 for image input, and a printer 2 for image output.
3 and 3.

FIG. 2 is a flow chart of the digital mosaic creation work in the system of FIG. Also, FIG.
FIG. 3 is a diagram schematically showing a method of two-dimensionally creating a digital mosaic photographic map by the method of the present invention for easy understanding. An embodiment of the method of the present invention will be described below with reference to these drawings.

First, as shown in step 101 in FIG. 2, a map and an aerial photograph around the mosaic creation area are collected. Then, as shown in step 102, the scanner 22 is used to convert the images of the collected map and aerial photograph from analog data into digital data, which are taken into the computer 10 as a map image file and a photograph image file, respectively. For example, it is stored in the hard disk 21.

Next, the digital mosaic application program 13 is activated, and as shown in step 103 in FIG. 2, the digital image data of the map image file and the photographic image file stored in the hard disk 21 is used to display on the display 12. The image of the map and photograph is displayed. Then, as shown in step 104, the outline of polygon division is determined using the image displayed on the CRT 12. The points to keep in mind when making this decision are:
There are the following four. (A) Points that are easy to select on the photographic image are polygon element points. (B) It is desirable to use polygonal points as the points that must be matched on the map. (C) The number of polygon elements is preferably 3 or 4. (D) One polygon is within the area of one corresponding photo (one photo image file).

The polygon thus determined is displayed on the map image. That is, the outline of polygon division is displayed as line data on the map on the screen. This draft is subject to change when measuring corresponding points on the photo. Then, as shown in step 105 of FIG. 2, the corresponding points on the photograph are designated. This is done as follows.

A point on the photograph corresponding to the element point of each polygon designated on the map is designated. When deciding the outline of polygon division on the map, it is necessary to select points that are easy to select on the photograph. However, if it is found difficult to specify the corresponding points at this stage, the polygon element points on the map are changed at the same time. The same applies when the point (d) to be noted when determining the outline plan is violated.

While enlarging and reducing the map image and photographic image displayed on the screen, the coordinates on the image of the polygon element corresponding points on the photographic image are measured. Store the measured coordinates of polygon element points as a parameter file,
As shown in 06 and 107, the correspondence between the polygon element points is checked by the residual calculated by performing the low-order transformation on each corresponding polygon recorded in the parameter file in the map image and the photograph image. The polygon element points are finally determined by.

Correspondence check of polygon element points is performed by residuals calculated by performing low-order transformation (Hell-Mart transformation or affine transformation) on each corresponding polygon in the map image and photographic image recorded in the parameter file. However, if a large residual is detected here, it is possible that the corresponding points on the map image or photographic image are incorrectly specified. Then, the element points are measured again. Figure 2
Step 108 of FIG.

Now, the output of residuals by the low-order projective transformation in step 106 will be described in more detail.
Usually, in the case of coefficient determination by the least squares method, calculation is performed using a large number of points, and corresponding points are checked from the degree of residual error generation. However, when the digital mosaic is created, the corresponding points cannot be checked as they are because the residuals are set to 0. Therefore, by using a conversion equation of a lower order than the conversion method, the residual is detected and the corresponding points are checked. The low-order conversion formula is as follows.

When there are 3 polygon element points: Helmert transformation (2 points, residual error 0) X = ax + by + c Y = -bx + ay + d When there are 4 polygon element points, affine transformation (3 points residual error 0) X = ax + by + c Y = Dx + ey + f Here, if a large residual error is detected, the correspondence of the polygon element points may be incorrect, so the coordinates of the element points are checked again.

After the polygon is finally determined in this way, the process proceeds to the digital mosaic processing of step 109 in FIG. 2, and the image is geometrically corrected with the determined polygon as a unit. Coefficients for affine transformation or pseudo affine transformation for performing this geometric correction are obtained, and a coefficient file for each polygon is created and stored. This coefficient file is a working file for creating a digital mosaic by this, and the coefficients corresponding to all polygons are stored in this file.

The image corresponding to the inside of each of the determined polygons is fitted while performing geometric correction. The geometric transformation of the image uses affine transformation or pseudo affine transformation. The usage is as follows. When there are 3 polygon element points, affine transformation (residual 0 at 3 points) X = ax + by + c Y = dx + ey + f When there are 4 polygon element points, pseudo affine transformation (residual 0 at 4 points) X = axy + bx + cy + d Y = exy + fx + gyy + h Is to suppress the occurrence of residuals when determining coefficients using the least squares method. As a result, the residual error becomes 0, and the polygon element points (orientation points) always take positions that match the map.
The geometric correction methods described above are summarized in the table of FIG.

Below, the procedure of the digital mosaic processing performed in step 109 is as follows. First, a mosaic image creation table corresponding to the scale of the map is prepared, and it is determined which polygon each point on the table is inside. An algorithm called a vertical straight line algorithm is effective for this determination. When it is determined that a point is inside a polygon, the photo image file and coefficient file corresponding to that polygon are called, and the coordinates of this point are converted using the coefficient corresponding to this polygon. . The new coordinate value thus obtained becomes the corresponding point on the photographic image. The color information of this corresponding point becomes the color information of the old coordinates on the table. By repeating this operation at all points on the table, one digital mosaic image is created. The data of the digital mosaic image created in this way is temporarily stored and saved in the hard disk 21.

The digital mosaic image data thus created is printed out by the printer 23 as shown in step 110 of FIG. 2 to obtain a digital mosaic photo map.

Finally, although it may overlap, an outline of the method for two-dimensionally creating a digital mosaic photographic map according to the present invention as described above will be described. Keep it.

First, a plurality of aerial photographs, which are the original data for creating a mosaic, are converted from analog to digital. Areas used for mosaic on these digital image data are set as polygons. This polygon is recorded as a set of polygon elements having coordinates (columns, lines) on the digital image data. Next, polygons corresponding to the above-mentioned polygons are set on the map corresponding to the mosaic creation area. This polygon is recorded as a set of polygon elements on an arbitrary coordinate system. This coordinate system is automatically converted into the coordinate system (column, line) of the mosaic image data. Next, the coefficient for performing the pseudo affine transformation is calculated for each polygon corresponding to the digital image data and the map by using the least square method. Where the number of elements in each polygon is 4
If the number is individual, the residual by the method of least squares will be 0, and the polygon element points will always coincide with those on the map.

Next, a mosaic image forming buffer corresponding to the map is prepared, and it is checked whether each point is inside or outside each polygon on the map. When it is determined that a certain target point is inside a polygon, a file including the polygon on the digital image data corresponding to the polygon is called. Then, the pseudo affine transformation is performed on the coordinates of this target point using the coefficient corresponding to this polygon. The new coordinates thus obtained become the coordinates of the corresponding points on the digital image data. The color information of the corresponding point on the digital image data is used as the color information of the target point on the buffer.
One digital mosaic image data is created by making the above-mentioned judgment for all the areas of this buffer corresponding to the map.

As described above, when it is desired to match two data such as a map and an aerial photograph, it is possible to make a rough correction (with the whole as one surface), but partial distortion naturally occurs. However, according to the method of the present invention, it is possible to remove geometric distortion between two media such as a map and an aerial photograph, and to accurately match the aerial photograph with a reference map.

Further, in the method of the present invention, geometric transformation processing of digital data is performed by using affine transformation or the like, and distortion is partially removed only in each patch (portion surrounded by 4 points or 3 points). The geometrical correction of the whole is performed by continuously connecting these. By combining the image processing technology according to the conversion formula and the technology for determining the inside of a polygon, it is possible to create an image in which the whole geometrically fit by repeating the partial geometric correction.

Furthermore, regarding the density and color adjustment method when performing aerial photography mosaic, the density adjustment coefficient is calculated by the least square method using the density value of the reference point position acquired for geometric correction at the joining point. Obtain and adjust the joint.

[0031]

The two-dimensional mapping and photographic mapping can be performed very easily and inexpensively.

Therefore, not only the creation of a three-dimensional map and an orthophoto, but also a cheaper two-dimensional map and an orthophoto can be provided, so that a wide range of customer needs can be met.

Since a two-dimensional photographic map can be created very easily and inexpensively from aerial photographs, for example, it is possible to reduce the cost of correcting the map according to the secular change of the landform of a wide range of forests and mountains. Will be able to do it.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a system for carrying out a method for two-dimensionally creating a digital mosaic photographic map according to the present invention.

2 is a diagram showing a flowchart of a digital mosaic creation operation in the system of FIG.

FIG. 3 is a diagram schematically showing a method of two-dimensionally creating a digital mosaic photographic map by the method of the present invention for easy understanding.

FIG. 4 is a table showing a summary of geometric correction methods used in the method of the present invention.

[Explanation of symbols] 10 computers 11 keyboard 12 display 13 Digital Mosaic Application Program 21 hard disk 22 Scanner 23 Printer

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G09B 29/00-29/14

Claims (3)

(57) [Claims] 1. A method of two-dimensionally creating a digital mosaic photo map, in which a map and a photo around a mosaic creation area are collected, image data of the map and the photo are converted from analog data to digital data, and A map image file and a photo image file are stored, the map and photo images are displayed using the digital image data of the map image file and the photo image file, and a schematic plan of polygon division using the displayed image , The determined polygon is displayed on the map image, the map image and the photographic image displayed on the screen are enlarged,
While reducing, the coordinates of the polygon element corresponding points on the photographic image are measured, the coordinates of the measured polygon element points are stored as a parameter file, and the map image and photographic image recorded in the parameter file are used. The polygon element points are finally determined by performing a low-order transformation on each corresponding polygon and checking the correspondence of the polygon element points by the residuals calculated, and for the polygons finally determined Then, a coefficient file for geometric correction is obtained and a coefficient file for each polygon is created and stored. A mosaic image creation table corresponding to the scale of the map is prepared, and each point on the table is inside which polygon. If it is determined that a certain point is inside a polygon, it is a photo image file corresponding to that polygon. And the coefficient file is called, the coordinates of this point on the table are converted by using the coefficient corresponding to this polygon, the coordinate value of the corresponding point on the photographic image is obtained, and the color information of this corresponding point is displayed on the table. The method is characterized in that the digital coordinate image is created by repeating the above process for all points on the table by using the color information of the old coordinates of the above, and creating a digital mosaic photo map. 2. The method according to claim 1, wherein the low-order transform is a Helmert transform or an affine transform. 3. The method according to claim 1, wherein the geometric correction is performed by an affine transformation or a pseudo affine transformation.