Menu View > Index Calculator > Sidebar > 3. Index Map

Index > Interface > Menu View > Index Calculator > Sidebar  Previous  |  Next 

 

 
Access: On the Menu bar, click View > Index Calculator (available once step 1. Initial Processing has been completed). The Index Calculator sidebar is displayed on the right of the main window. For information about the sidebar's display possibilities: Displaying bars.

View_Index_Calculator.png

On the left part of section 3. Index Map, there is an arrow that allows the user to show/hide the section by clicking on it:

  •  By default section 3. Index Map is visible. 
  •  Section 3. Index Map is not visible.

Index_Calculator_1.png


An Index Map is a single band image where each pixel value is computed using a mathematical formula combining the band information of the Reflectance Maps

The following information is displayed:

  • Name: List of available indices. The icon shown before the index name is:
    • database.png The index exists in the Pix4Dmapper index database. 
      For more information about the Pix4Dmapper index database list: Pix4Dmapper Index Database List.
    • document.png The index was created / edited by the user in this project.
    • user.png The index was created / edited by the user in another project (on the same computer) that was closed and saved. 
  • Formula: Displays the formula associated with the selected index. 
  • Formula Status icon: Next to the Formula there is an icon:
    • ok.png The formula is valid.
    • warning.png The formula is incomplete or contains undefined band names.
  • Index Status icon: If next to the Generate button there is
    • done.png The index has been generated.
  • Generate: Generates a single band GeoTiff image. Each pixel's value is computed by applying the formula to the corresponding pixel of the Reflectance Map(s). It is grayed out if the user-defined index formula is not valid.
  • Help: Opens the Pix4Dmapper help.
 
Important: For more information about the generated files and where they are stored: Menu Process > Processing Options... > 3. DSM, Orthomosaic and Index > Index Calculator.

The section 3. Index Map also displays information about the generated index band. The following information is displayed:

  • Band: The Index Map has only one band to be displayed (band1).
  • Min: Minimum pixel value.
  • Avg: Average pixel value.
  • Max: Maximum pixel value.
  • Stdev: Standard deviation of pixel values.
  • Var: Variance of pixel values.

If the selected index has not been generated, it displays: "Selected idex map not yet generated."

 
Index Map not generated   Index Map generated
 
Note: 
  • The Index Maps are calculated using some specific band(s) from one or more groups of images. Therefore, information from one or more Reflectance Maps may be used.
  • If a Region/Regions drawn, the Index Maps and Colored Index Maps will be generated only for this region/regions.
  • Colored Index Maps are generated by applying the defined coloring rules to the Index Maps. They are raster files with RGB values.

 

Index > Interface > Menu View > Index Calculator > Sidebar  Previous  |  Next 
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3 comments

  • Steven Shirtliffe

    If you have drawn multiple regions on your orthomosaic does the "Avg" under the "Index Map" section express the average over all of the regions or simply the selected region? It appears to not change as you move from region to region however the differences in my particular dataset may just not be large enough to be registered. 

  • David MacTaggart

    If you have drawn multiple regions on your orthomosaic does the "Avg" under the "Index Map" section express the average over all of the regions or simply the selected region? It appears to not change as you move from region to region however the differences in my particular dataset may just not be large enough to be registered.

  • Momtanu (Pix4D)

    David,

    It gives you the average of all regions. It might be the average values of the pixels you are adding are kind of the same. The NDVI mean is accumulation when you are adding multiple regions.

    If you need an average of one single region (and you have multiple regions)

    What you can do is:

    • Add region. Rename the region so it's easier for you. Draw the regions (you can draw multiple polygons (replicates) for one region if you have more than one area (replicates) under the same treatment and you would like to know the mean NDVI of each treatment). So region 1 can be treatment 1 (maybe 3 replicates), region 2 can be treatment 2 (with 4 replicates, each replicate 1 polygon). 
    • Draw region 1 first (might be multiple polygons) and export. No need to generate NDVI now
    • Draw region 2 and export
    • Now import region 1. Generate NDVI. You get the mean NDVI of that region
    • Now import region 2. Region 1 will automatically disappear. Generate NDVI. This one is the mean NDVI of region 2.

    Also, If you export all regions together, when you import them, it gets imported together and results in the mean NDVI of all regions

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