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Poor Raster Rendering with Small Values (v100.4)

Question asked by keith.gemeinhart on Jul 16, 2019

First, a general question about future versions of the runtime: Are there any plans to enhance the raster renderers or add a classify renderer? 

 

More generally, I'm doing some raster analysis and adding them to the map by creating a RasterLayer with the file path:

 

var rlayer = new RasterLayer(path);
rlayer.Id = id;
rlayer.Renderer = RendererFactory.GenerateRenderer(product, path);
rlayer.Opacity = 0.6;
rlayer.IsVisible = false;
layers.Add(rlayer);

 

RendererFactory is a class I wrote that chooses the renderer properties based on the type of file. The problem I'm running into is that even when I set the renderer properties to match the symbology in Pro, often times it doesn't render or has a very narrow range of colors. Anecdotally, this seems more likely to happen when the raster values are small (<1), or have a small range, or a small number of unique values. But I haven't really tried to narrow it down.

 

This is an example of one my rasters in Pro:

 

 

Here is it's corresponding symbology:

 

The same raster rendered on my map looks like this:

 

Here are the rendering parameters:

IEnumerable<double> myGammaValues = new List<double>() { 1.0 };

var std = new StandardDeviationStretchParameters(2.0);
var numColors = Math.Ceiling(max - min);
if (numColors < 16)
numColors = 16;
ColorRamp myColorRamp = ColorRamp.Create(PresetColorRampType.Elevation, (uint)numColors);

var rendrr = new StretchRenderer(std, myGammaValues, true, myColorRamp);
return rendrr;

 

The result is the same if I change color ramp to DemScreen or if I use Min/Max parameters for the stretch renderer.

 

However, if I set the layer renderer to null, I actually get a better rendering (albeit grayscale):

 

 

Any advice on how to improve my raster rendering????

 

P.S. Sample raster attached.

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