WO2014167174A1 - A method for measuring basal area of trunks in a forest based on decoding of photos taken of the forest cover - Google Patents

A method for measuring basal area of trunks in a forest based on decoding of photos taken of the forest cover Download PDF

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Publication number
WO2014167174A1
WO2014167174A1 PCT/FI2014/000005 FI2014000005W WO2014167174A1 WO 2014167174 A1 WO2014167174 A1 WO 2014167174A1 FI 2014000005 W FI2014000005 W FI 2014000005W WO 2014167174 A1 WO2014167174 A1 WO 2014167174A1
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WO
WIPO (PCT)
Prior art keywords
photos
trunks
forest
sample
measuring
Prior art date
Application number
PCT/FI2014/000005
Other languages
French (fr)
Inventor
Simo KIVIMÄKI
Timo ROUVINEN
Original Assignee
Trestima Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Trestima Oy filed Critical Trestima Oy
Priority to EP14783438.6A priority Critical patent/EP2986930B1/en
Publication of WO2014167174A1 publication Critical patent/WO2014167174A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/28—Measuring arrangements characterised by the use of optical techniques for measuring areas
    • G01B11/285—Measuring arrangements characterised by the use of optical techniques for measuring areas using photoelectric detection means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
    • G01B5/0035—Measuring of dimensions of trees
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/60—Analysis of geometric attributes
    • G06T7/62—Analysis of geometric attributes of area, perimeter, diameter or volume

Definitions

  • This invention relates to a method for measuring of basal area of trunks in a forest, said method based on decoding photos taken of the forest cover, wherein the method comprising steps of:
  • US patent publication no. 7315794 discloses a timber survey system performing the steps of: placing a first reference point and a second reference point on a tree trunk, wherein an actual distance between the first reference point and the second reference point is a known distance, capturing an image of that portion of the tree trunk having the reference points placed on the trunk; measuring on the image an image distance, between the first reference point and the second reference point; measuring on the image an image distance, between the left outer boundary and the right outer boundary of the tree trunk; and calculating an actual distance, between the left outer boundary and the right outer boundary of the tree trunk.
  • the method according to the invention facilitates especially work in the forest when determining the basal area of the forest cover.
  • the measuring person only takes several photographs when walking in the area being measured.
  • the tree species do not need to be identified in the forest.
  • the number of trees as well as trunk breadths do not need to be known because these will be later measured and determined from the sample photos.
  • Figure 1 describes a digital photo of a forest for measuring of its basal area per area unit.
  • Figure 2 describes a camera calibration arrangement.
  • Figure 1 is a sample photo taken by a digital camera 9 like mobile camera device.
  • the horizontal view angle value a of the camera is known or said angle value must be measured.
  • the horizontal view angle value a can be measured according to figure 2 by taking a calibration photo of a scaled flexible band 10 which locates at a distance R from the camera 9. Distance R is 1 m in this example.
  • the band 10 has been bent towards the camera 9 in a circle shape also with radius R.
  • the scaled band 10 has been equipped with an angle scale - 60° to + ⁇ 60° and in addition a line segment 11, the length of which is in this case 2 cm. From the taken photo the horizontal angle value a of the camera 9 can be seen by reading it from the scale 10 in the photo.
  • the visible portion of the band 10 indicates the angle value a.
  • the user takes via mobile device like digital camera 9 or mobile camera sample photos 2 of the measured forest.
  • the camera device 9 comprises client program which maintains view angle value a to be constant and sends photos 2 to a database of web server system.
  • the analyzing of the photos 2 is carried out in crowdsourcing wherein some elected persons or group of persons can be received photos 2 via Internet for analyzing.
  • a person who is measuring number of trunks 3 from the sample photo 2 locating in the display 1 moves cursor from one side of a trunk 3 to the other side and clicks by means of a mouse the start and end points of the trunk breadth.
  • the figure 1 shows some trunks 3 which have measured by cursor, as seen marked with reference number 4.
  • the person measures by this way using cursor at least all possible trunks 3 in the photo which may have needed breadth.
  • the measuring height on the trunk 3 is preferable 1,3 m.
  • the person may measure also a little narrower trunks because this does not cause any mistake when the program will reject all trunks 3 whose breadth does not have the needed number of pixels calculated according to the formula A above.
  • the analyzing person defines from the sample photos 2 existing tree species and stores simultaneously also the trunk 3 whose breadth is marked by the cursor.
  • the analyzing person has in his display 1 function keys 5 - 8 by means of which she/he can elect functions like storing, sending data, electing tree species, making corrections.
  • the measuring person is carrying out photo decoding via internet when received sample photos 2 of the forest area whose basal area of trunks per area unit must be measured.
  • the analyzing person receives photos 2 she he also receives operation system which is steering the analyzing.
  • the analyzing person only observes and elects tree species of each trunk 3 whose breadth she/he is marking by a cursor on the display 1 which is presenting sample photo 2.
  • the operation system comprises function to return photo analyzing from the analyzing person to the database of the measuring organization. From each photo 2 a basal area value (m2) / hectare can be measured from the calculated and accepted number of the trunks 3 by means of the formula
  • Basal area (m2) number of trunks x Q x 360°
  • This formula B gives result per hectare when the camera 9 has been calibrated by the manner described above and the pixel number is calculated per line segment 11 whose length is 2 cm.
  • the basal area can be calculated for example square yard per acre.
  • a lot of landscape photos 2 are taken of the forest cover wherein average value is calculated of the numbers of the trunks 3 elected from each photos 2.
  • the analyzing person elects from the sample photo 2 when surveyed it on the display 1 such a trunks 3 that can be accepted as sample trunks based on the breadth of said trunk 3 by utilizing on the display moved line segment the length of which points out if the trunk 3 could be accepted or not. Also can be used method to click with the cursor in both sides of the trunk, as can be seen from the figure 1 pointed with reference number 4.
  • the person makes in a web server a photo analysis of those photos 2 whose analysis done by machine vision has been rejected. Also the person stores a location data with each sample photo 2.
  • the location data is utilized in determination of the basal area calculation by dividing measured area into smaller areas by means of the location data and calculating the basal area for of each of these areas separately
  • the sending of the sample photo s 2 from the camera device to web server can be arranged to happen automatically. Also the real time information of basal area and tree species distribution can be sent to the camera device during the measuring session.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Botany (AREA)
  • Engineering & Computer Science (AREA)
  • Geometry (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Theoretical Computer Science (AREA)
  • Management, Administration, Business Operations System, And Electronic Commerce (AREA)
  • Image Analysis (AREA)

Abstract

Method for measuring of basal area of trunks in a forest, said method based on decoding photos taken of the forest cover, wherein the method comprising steps of: using a camera (9), whose horizontal view angle value (a) is known and this value is kept constant when taking sample photos for measuring, taking sample photos (2) by means of the camera (9) of forest cover in an area to be surveyed, wherein measuring data is included in each photo (2), storing photos (2) in a database for analyzing, and wherein storing the taken sample photos (2) of the forest cover into database created in a web server, calculating in a web server the numbers of trunks from the sample photos (2) taken of the forest cover and calculating such a trunk (3) to add said number, whose breadth as pixels exceeds the limit value of pixels measured for the device performing photography.

Description

A METHOD FOR MEASURING BASAL AREA OF TRUNKS IN A FOREST BASED ON DECODING OF PHOTOS TAKEN OF THE FOREST COVER
Background of the Invention This invention relates to a method for measuring of basal area of trunks in a forest, said method based on decoding photos taken of the forest cover, wherein the method comprising steps of:
- using a camera, whose horizontal view angle value is known and this value is kept constant when taking sample photos for measuring,
- taking sample photos by means of the camera of the forest cover in an area to be surveyed, wherein measuring data is included in each photo,
- storing photos in a database for analyzing.
Cross reference to related publications
Earlier is known a measuring method of biomass in forest from the EP application no. 2163846 which discloses laser distance measuring, analysis of digital photographs, machine vision and GPS location data. The intellectual mobile phone contains camera, GPS and extra sensors that logs in a server and databases. In the measurement and login device the programs calculate the analysis data in the real time measurements.
US patent publication no. 7315794 discloses a timber survey system performing the steps of: placing a first reference point and a second reference point on a tree trunk, wherein an actual distance between the first reference point and the second reference point is a known distance, capturing an image of that portion of the tree trunk having the reference points placed on the trunk; measuring on the image an image distance, between the first reference point and the second reference point; measuring on the image an image distance, between the left outer boundary and the right outer boundary of the tree trunk; and calculating an actual distance, between the left outer boundary and the right outer boundary of the tree trunk.
The above referred methods have as disadvantages that at least part of the measurements must be done in a forest like reference measuring and distance measuring, further in the known methods unreliable machine vision is used, wherein especially said machine vision cannot reliable identify different tree species. Summary of the Invention
By the method according to the invention an essential improvement can be achieved in surveying basal area and further in determining biomass or tree quantity of the forest based on said basal area per area unit. Characteristics for the method according to the invention is that
- storing the taken sample photos of the forest cover into database created in a web server,
- calculating in a web server the numbers of trunks from the sample photos taken of the forest cover and calculating such a trunk to add said number, whose breadth as pixels exceeds the limit value measured for the device performing photography,
- when the horizontal angle value a of the camera is smaller than 360°, the number of trunks is multiplied by value 3607 α , and
- determining the basal area or basal areas per tree species of the forest cover in the surveyed forest area per area unit from the number of the trunks. The method according to the invention facilitates especially work in the forest when determining the basal area of the forest cover. The measuring person only takes several photographs when walking in the area being measured. The tree species do not need to be identified in the forest. The number of trees as well as trunk breadths do not need to be known because these will be later measured and determined from the sample photos. Brief Description of the Drawings
In the following the invention is described more detailed by referring to the
accompanying drawings where:
Figure 1 describes a digital photo of a forest for measuring of its basal area per area unit. Figure 2 describes a camera calibration arrangement. Figure 1 is a sample photo taken by a digital camera 9 like mobile camera device. The horizontal view angle value a of the camera is known or said angle value must be measured.
If the horizontal view angle value a is not known it can be measured according to figure 2 by taking a calibration photo of a scaled flexible band 10 which locates at a distance R from the camera 9. Distance R is 1 m in this example. The band 10 has been bent towards the camera 9 in a circle shape also with radius R. The scaled band 10 has been equipped with an angle scale - 60° to +■ 60° and in addition a line segment 11, the length of which is in this case 2 cm. From the taken photo the horizontal angle value a of the camera 9 can be seen by reading it from the scale 10 in the photo. The visible portion of the band 10 indicates the angle value a.
In the following it is from the calibration photo measured number of pixels included in said 2 cm line segment 11. This pixel number is changed to native resolution pixels in the following way: (A) Trunk breadth
measured number of pixels
limit value m pixels =
native horizontal resolution / horizontal resolution of photo
The user takes via mobile device like digital camera 9 or mobile camera sample photos 2 of the measured forest. The camera device 9 comprises client program which maintains view angle value a to be constant and sends photos 2 to a database of web server system. In this invention the analyzing of the photos 2 is carried out in crowdsourcing wherein some elected persons or group of persons can be received photos 2 via Internet for analyzing.
A person who is measuring number of trunks 3 from the sample photo 2 locating in the display 1 (fig. I), moves cursor from one side of a trunk 3 to the other side and clicks by means of a mouse the start and end points of the trunk breadth. The figure 1 shows some trunks 3 which have measured by cursor, as seen marked with reference number 4. The person measures by this way using cursor at least all possible trunks 3 in the photo which may have needed breadth. The measuring height on the trunk 3 is preferable 1,3 m. The person may measure also a little narrower trunks because this does not cause any mistake when the program will reject all trunks 3 whose breadth does not have the needed number of pixels calculated according to the formula A above.
The analyzing person defines from the sample photos 2 existing tree species and stores simultaneously also the trunk 3 whose breadth is marked by the cursor. The analyzing person has in his display 1 function keys 5 - 8 by means of which she/he can elect functions like storing, sending data, electing tree species, making corrections.
In this invention the measuring person is carrying out photo decoding via internet when received sample photos 2 of the forest area whose basal area of trunks per area unit must be measured. When the analyzing person receives photos 2 she he also receives operation system which is steering the analyzing. The analyzing person only observes and elects tree species of each trunk 3 whose breadth she/he is marking by a cursor on the display 1 which is presenting sample photo 2. The operation system comprises function to return photo analyzing from the analyzing person to the database of the measuring organization. From each photo 2 a basal area value (m2) / hectare can be measured from the calculated and accepted number of the trunks 3 by means of the formula
(B) Basal area (m2) = number of trunks x Q x 360°
a
This formula B gives result per hectare when the camera 9 has been calibrated by the manner described above and the pixel number is calculated per line segment 11 whose length is 2 cm. By same principle the basal area can be calculated for example square yard per acre. Then must be different line segment length or radius R used. Q is relascope factor. This factor is 1 when R = 1 m and length of the used line segment 11 is 2 cm.
In one embodiment of the method a lot of landscape photos 2 are taken of the forest cover wherein average value is calculated of the numbers of the trunks 3 elected from each photos 2.
In another embodiment of the method the analyzing person elects from the sample photo 2 when surveyed it on the display 1 such a trunks 3 that can be accepted as sample trunks based on the breadth of said trunk 3 by utilizing on the display moved line segment the length of which points out if the trunk 3 could be accepted or not. Also can be used method to click with the cursor in both sides of the trunk, as can be seen from the figure 1 pointed with reference number 4.
In another embodiment the person makes in a web server a photo analysis of those photos 2 whose analysis done by machine vision has been rejected. Also the person stores a location data with each sample photo 2.
Further in the invented method the location data is utilized in determination of the basal area calculation by dividing measured area into smaller areas by means of the location data and calculating the basal area for of each of these areas separately According to the invention the sending of the sample photo s 2 from the camera device to web server can be arranged to happen automatically. Also the real time information of basal area and tree species distribution can be sent to the camera device during the measuring session.

Claims

1. Method for measuring of basal area of trunks in a forest, said method based on decoding photos taken of the forest cover, wherein the method comprising steps of: - using a camera (9), whose horizontal view angle value (a) is known and this value is kept constant when taking sample photos for measuring,
- taking sample photos (2) by means of the camera (9) of forest cover in an area to be surveyed, wherein measuring data is included in each photo (2),
- storing photos (2) in a database for analyzing,
characterized in that
- storing the taken sample photos (2) of the forest cover into database created in a web server,
- calculating in a web server the numbers of trunks from the sample photos (2) taken of the forest cover and calculating such a trunk (3) to add said number, whose breadth as pixels exceeds the limit value of pixels measured for the device performing photography,
- when the horizontal angle value (a) of the camera (9) is smaller than 360°, the number of trunks (3) is multiplied by value 3607 α ,
- a person or group of persons using web browser connected to a cloud service carryout the election of the trunks (3) and define their tree species, and
- determining the basal area or basal areas per tree species of the forest cover in the surveyed forest area per area unit from the number of the trunks (3).
2. Method according to claim 1 characterized in that a person or group of persons working via web browser connected to a cloud service are connected to the database, from where sample photos (2) and computer software for performing the work can be obtained.
3. Method according to claim 1 characterized in that a lot of photos (2) are taken of the forest cover wherein average value is calculated of the numbers of the trunks (3) in each photos.
4. Method according to claim 1 characterized in that sample photos (2) are taken as landscape photos for determining the basal area.
5. Method according to claim 1 characterized in that from the sample photo (2) surveyed on the display (1) the trunks (3) that can be accepted as sample trunks are elected based on the breadth of said trunk (3) utilizing a line segment moved on the display or movement of a cursor from one side of the trunk (3) to another.
6. Method according to claim 1 characterized in that in a web server a person entries via web browser to look the sample photos (2) wherein said person identifies the tree species on the display (1) and picks up trunks (3) for trunk calculation and stores the measuring.
7. Method according to claim 6 characterized in that the web server comprises a computer software, which removes from the group of trunks elected by the person the trunks whose breadth does not fulfill the breadth requirement.
8. Method according to claim 6 characterized in that in the web server the person elects the tree species and stores the measuring utilizing for example function keys (5, 6, 7, 8).
9. Method according to claim 1 characterized in that in the web server the person makes a photo analysis of those photos (2) whose analysis done by machine vision has been rejected.
10. Method according to claim 1 characterized in that a location data is stored with each sample photo (2).
11. Method according to claim 1 characterized in that the location data is utilized in determination of the basal area calculation by dividing measured area into smaller areas by means of the location data.
12. Method according to claim 1 characterized in that the sending of the sample photos (2) from the camera device to web server is arranged to happen automatically.
13. Method according to claim 1 characterized in that real time information of basal area and tree species distribution can be sent to the camera device during the measuring session.
PCT/FI2014/000005 2013-04-11 2014-04-11 A method for measuring basal area of trunks in a forest based on decoding of photos taken of the forest cover WO2014167174A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP14783438.6A EP2986930B1 (en) 2013-04-11 2014-04-11 A method for measuring basal area of trunks in a forest based on decoding of photos taken of the forest cover

Applications Claiming Priority (2)

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FI20130106 2013-04-11
FI20130106A FI124950B (en) 2013-04-11 2013-04-11 Procedure for measuring the root surface of tree trunks in a forest on the basis of interpretation of photos taken on a tree stock

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112113616A (en) * 2020-09-18 2020-12-22 山东省地矿工程勘察院 Geographic information collection system based on GIS
CN113175918A (en) * 2020-01-08 2021-07-27 北京林业大学 Technical method for measuring vegetation coverage and density by smart phone

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Publication number Priority date Publication date Assignee Title
US20020191198A1 (en) * 2001-06-18 2002-12-19 Dunne Jeremy G. Upper stem diameter measurement and basal area determination device and method for utilization in timber cruising applications
WO2003094109A2 (en) * 2002-05-03 2003-11-13 International Hardwood Resources, Inc. Method od feature identification and analysis
US7315794B1 (en) 2004-03-23 2008-01-01 Willis Frank L Timber survey process and apparatus
EP2163846A1 (en) * 2008-09-02 2010-03-17 Vilho Kalevi Pietikäinen A measuring method of biomass in forest
US20120202515A1 (en) * 2011-02-09 2012-08-09 Stanford University Smartphone-based asset management system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020191198A1 (en) * 2001-06-18 2002-12-19 Dunne Jeremy G. Upper stem diameter measurement and basal area determination device and method for utilization in timber cruising applications
WO2003094109A2 (en) * 2002-05-03 2003-11-13 International Hardwood Resources, Inc. Method od feature identification and analysis
US7315794B1 (en) 2004-03-23 2008-01-01 Willis Frank L Timber survey process and apparatus
EP2163846A1 (en) * 2008-09-02 2010-03-17 Vilho Kalevi Pietikäinen A measuring method of biomass in forest
US20120202515A1 (en) * 2011-02-09 2012-08-09 Stanford University Smartphone-based asset management system

Non-Patent Citations (3)

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Title
MOLINIER ET AL.: "Automatic tree stem delineation supporting forest inventory'.", GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS) - IEEE, 24 July 2011 (2011-07-24), pages 4465 - 4468, XP032242343 *
MOLINIER M ET AL.: "GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS", 24 July 2011, IEEE, article "Automatic tree stem delineation supporting forest inventory", pages: 4465 - 4468
See also references of EP2986930A4

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113175918A (en) * 2020-01-08 2021-07-27 北京林业大学 Technical method for measuring vegetation coverage and density by smart phone
CN113175918B (en) * 2020-01-08 2022-09-06 北京林业大学 Technical method for measuring vegetation coverage and density by smart phone
CN112113616A (en) * 2020-09-18 2020-12-22 山东省地矿工程勘察院 Geographic information collection system based on GIS
CN112113616B (en) * 2020-09-18 2022-09-02 山东省地矿工程勘察院 Geographic information collection system based on GIS

Also Published As

Publication number Publication date
EP2986930B1 (en) 2022-06-29
EP2986930A1 (en) 2016-02-24
FI20130106A (en) 2014-10-12
FI124950B (en) 2015-04-15
EP2986930A4 (en) 2017-01-18

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