Specify "NDVI Shader" for output file

rdptwhrdptwh Global Mapper UserPosts: 11
Hi,
I need to create NDVI layers from a large number of NIR NAIP images. I've written a script that correctly creates a NDVI layer for each NAIP quarter quad, but they are gray scale   and I can't for the life of me  figure out how to to export them with the NDVI shader.
I can load the files back into GM and apply the shader, but ...
Any Suggestions?
My script follows
--bob

GLOBAL_MAPPER_SCRIPT VERSION=1.00
UNLOAD_ALL

// Loop over all .tif files in a folder and convert them
DIR_LOOP_START DIRECTORY="C:\Users\rdp\NDVI\test\" FILENAME_MASKS="*.tif" TYPE="GEOTIFF" \
     LABEL_FIELD_FORCE_OVERWRITE="NO" LABEL_FORMAT_NUMBERS="YES" LABEL_PRECISION="-1" \
     LABEL_REMOVE_TRAILING_ZEROS="YES" LABEL_USE_SCIENTIFIC_NOTATION="NO" LOAD_FLAGS="0~0~0~4~0~0" \
     CLIP_COLLAR="NONE" SAMPLING_METHOD="NONE" AUTO_CONTRAST="NO" CONTRAST_SHARED="YES" \
     CONTRAST_MODE="NONE" TEXTURE_MAP="NO"

// Import
IMPORT FILENAME="%FNAME_W_DIR%"
//Calculate NDVI
APPLY_FORMULA FILENAME="*" FORMULA="NDVI" OUTPUT_GRID=YES
//DEFINE_SHADER SHADER_NAME="NDVI Shader" BLEND_COLORS="YES" STRETCH_TO_RANGE="NO" SHADE_SLOPES="NO" \
//     SLOPES_PERCENT="NO" OVERWRITE_EXISTING="NO" SAVE_SHADER="YES"
//    -0.2,RGB(0,0,255)
//    0,RGB(255,255,255)
//    0.3,RGB(0,128,0)
//    0.6,RGB(0,64,0)
//END_DEFINE_SHADER
SET_VERT_DISP_OPTS SHADER_NAME="NDVI Shader"
//Export Raster
EXPORT_ELEVATION FILENAME="%DIR%%FNAME_WO_EXT%_ndvi.tif" TYPE=GEOTIFF BAND_BIT_DEPTH=32
UNLOAD_ALL

// End the loop
DIR_LOOP_END

Answers

  • bmg_bobbmg_bob Global Mapper Programmer Posts: 2,004
    Hello,

    When you export an elevation grid file, the data values are NDVI values, and don't include any color information. The shader can only be applied when you are viewing data in Global Mapper. 

    Do you still need the raw values in your data? If not, you can export the data as a raster image (EXPORT_RASTER script command). That will preserve the shader coloring, but not the NDVI values. You can also export both, then you will have an file containing the raw data, and another with the shaded view.

    Cheers,
    Bob
  • rdptwhrdptwh Global Mapper User Posts: 11
    Thanks Bob,
    I decided on your solution earlier today. My script now exports both a raster image and an elevation grid.
    I'm glad to hear that I found the correct solution
    regards
    --bob
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