WinSCANOPY: Canopy Structure and Solar Radiation Analysis
Image Analysis for Plant Science
Regent Instruments Inc. since 1991




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Analysis Process

This page illustrates the steps that lead to the analysis of an image in WinSCANOPY

1. Load an image
2. Specify the region to analyse
3. Sample identification
4. Analysis validation
5. Data saving

1. Load an image  

Image loading is done in a few mouse clicks (click the disk icon and select the image name from a list). WinSCANOPY then displays the image on screen.

2. Specify the region to analyse  

To analyse an image, you must indicate which region is the hemisphere. This can be done by three methods:

a) The easiest method is when you own a camera and lens calibrated and sold by Regent Instruments. In this situation WinSCANOPYreads from our calibration file the necessary parameters to identify the region to analyse, so the only thing you have to do to start the analysis is to click the image. This file indicates to WinSCANOPYwhere is the centre of the hemisphere, what is the radius that produces a 180 degrees field of view and how to compensate for lens distortions. These parameters can be overridden to reduce the field of view at the zenith or horizon for example.

b) You can specify the region to analyse interactively (Regular or Pro) . You can move and resize the hemisphere using mouse and keyboard keys commands.



c) You can specify the region to analyse with numerical parameters (the centre position and radius size in pixels). You can determine these experimentally. Although some freeware manufacturers claim this step is "easy", you will have to invest material resources and significant time to do this precisely (the final cost often being larger than buying a complete calibrated system ready to use).

3. Sample identification  

When you release the mouse button after the hemisphere creation,WinSCANOPYautomatically displays the sample identification window that allows you to set the information specific to the image being analysed. You can customize this window's information (choose which information is shown). Some of this information is used for the analysis, latitude and longitude are used to calculate solar paths for example, while the rest is simply reproduced in the data files along with the measurements. When you click OK in this identification window, the analysis begins and is displayed after completion.

The hemisphere’s diameter and position in the image are also saved in the measurements data file so these parameters can be verified after the analysis. The analysis data and settings are also saved with the image (in the same tiff file) and can be retrieved later by WinSCANOPY to recreate the analysis.

4. Analysis validation  

When the analysis is complete, it is visible in the main window. The sky grid, divided in the number of azimuthal and zenithal divisions that you choose, is displayed in yellow. Messages to the operator and partial analysis data are displayed to the left of the image. Detailes data are saved inWinSCANOPY's data files.


Additional information about a sky region can be displayed by clicking it in the image.

Suntracks, each containing the sun’s position in the image for different hours of a particular day, are displayed with rainbow-style colors (the color is related to the intensity of the radiation level above the canopy). The date is displayed close to it.

When you click a suntrack, information about its closest point to the clicked position is displayed. This includes the date, hour and instantaneous radiation value for that moment. Its data are also displayed in the graphic above the image and summarized to the left of the image.

Menus in the upper-right corner of the graphic (all versions except Mini) allow you to select the type of data and the relevant options you wish to be displayed. The available data are:

  1) Radiation level per hour of the day for the active suntrack  
  2) Radiation level per day  
  3)Gap fractions in function of zenith or azimuthal direction  
  4) Leaf angle distribution  
  5) Sunfleck frequency distribution (number in function of duration in minutes)  
  6) Sunfleck duration (total in minutes) per day of the growing season  
  7) Gaps size cumulative distribution  
  8) Leaf projection coefficient in function of zenith angle  
  9) Clumping index in function of zenith angle  
5. Data saving  

At the end of the analysis, data are automatically saved by WinSCANOPY in standard ASCII text format that is well adapted to manipulation into spreadsheet programs like Microsoft Excel. You have entire control on what is saved in data files (Regular, Pro). You can choose to save or not:

  1. The settings used to analyse the image, information about the camera, lens and the analyses hemisphere position and size.
  2. The measurement data (LAI, Openness, Radiations...).

Data produced by WinSCANOPY fall into these categories (the list below is incomplete):

  • Global data. These are measurements that have a single value for the entire image. Some examples of global data are the site factors, openness, daily radiation for the growing season, leaf area index and NDVI data (Pro NDVI version only). WinSCANOPY's analysis settings are also saved in the global data line along with the image information.
  • Gap fractions per sky region, per elevation ring and per direction. Openness per elevation ring.
  • Radiation per day. This include six data types: direct and indirect (diffuse), above and below canopy and total radiation. Radiation is clearly presented by day and month (10 June 2000) and not by Julian or decimal days (like day 322).
  • Leaf angle density and cumulative leaf angle density.
  • A table of the percentage of time that direct radiation is received at the photo location; per hour for each month.
  • Sunfleck distribution and duration.
  • Clumping index in function of zenith angle and per sky region.
  • Leaf projection coefficient in function of zenith angle.
  • Measured and theoretical gaps size distribution.