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Color Shaded Relief

by Technical Evangelist on ‎09-29-2015 01:36 PM - edited on ‎04-21-2016 05:47 AM by Technical Evangelist (2,435 Views)

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Description:

This model creates a color shaded relief file, using a raster elevation model as input. There are user defined parameters for the lighting source characteristics and the color ramp to be merged with the relief shading. The output is a 3-band color image. The desired band display order is 1/2/3 to red/green/blue with no stretch applied. You can use Preview to test your settings before writing to file. 

 

NOTE: If the Raster data connected to an Input port has been processed using any operator that uses neighboring pixels in calculations (such as the Relief operator), and the preview is displayed at a scale other than 1:1 with respect to the pixels of the original image or images, Preview will be calculated using resampled pixels. This means, for instance, that a Preview using Fit To Frame may look different than sending the raster data to an Output Raster and then viewing that raster using Fit To Frame. In this model, the shading in the Preview will look more drastic at anything other than 1:1. 

 

Also note that this Model is performing the equivalent of opening the raster elevation data as an Image Chain (File / Open / Raster as Image Chain..) and using the Relief Image Chain (with ERDAS IMAGINE 2015 onwards).

 

shaded_relief_v2-supplemental_redo.PNG

                                            Above: Input raster elevation model and output color shaded relief    

                                                                    Below: shaded_relief_v2.gmdx

shaded_relief_v2-2015.PNG

Input parameters:

Input DEM: (filename with path) of the input raster digital elevation file. Model assumes that there is 1 band. The vertical units are assumed to be meters.

Output Shaded Relief: (filename with path) of the output color shaded relief file. This file is 3-band (8 bits per band) and the desired band display order is 1/2/3 to red/green/blue.

Sun Azimuth: (integer)(default 315 - northwest) Illumination source angle in degrees, clockwise from north.

Sun Elevation: (integer)(default 45) Illumination source angle above the horizon.

Ambient Light: (float)(default 0.10000) Ambient light - range 0.0 to 1.0

Color Ramp: (integer)(default 2) Specifies the color ramp used in producing the output. The minimum to maximum elevation values contained in the input file will be scaled into these colors.

        1. BlueToGreenToRedToYellow
        2. ColorRampElevation1
        3. ColorRampElevation2
        4. ColorRampHeat
        5. ColorRampGrey

shaded_relief_v2-supplemental_2.PNG

Comments
by Technical Evangelist
‎10-28-2015 12:14 PM - edited ‎11-20-2015 07:47 AM

Excellent article!

 

Note that the Relief Image Chain provides similar (and more extensive) shading and coloring capabilities. To display a DEM using the Image Chain go to the File tab / Open / Raster as Image Chain.. option and select your DEM raster input file. If the DEM has Elevation Info associated with its header it will automatically display using the Relief Chain. If it doesn't it will probably default to the Panchromatic chain. If this is the case, on the Panchromatic tab / Settings group click the Image Chain pull down and select Relief. In the Color group you can then turn on the Use Colors option and experiment with different color ramps.

 

Unfortunately, until ERDAS IMAGINE 2016 is released, you cannot save the styled DEM to a new raster layer from the Image Chain. So this Spatial Model fills that gap until ERDAS IMAGINE 2016 is released.

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