How to average two rasters in ArcGIS JS API?

LJiang

Hello all,

I have two raster datasets (in arcgis image server) and I need to get an average of the two represented as one raster layer.  It can be easily achieved in ArcMap by "Spatial Analyst-->Map Algebra-->Raster Calculator" using "(Float(raster1) + Float(raster2))/2". And ArcPy can also do this using arcpy.sa module. I am wondering if it can be done in ArcGIS JavaScript API (Version 3.18).

It seems that the 'Local' function in Class: RasterFunction can do this, but I don‘t know how to do it. Any help please.

LJiang

Here is my code, but it seems this doesn't work.  

<SPAN class="keyword token">var</SPAN> rf1 <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">RasterFunction</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
rf1<SPAN class="punctuation token">.</SPAN>functionName <SPAN class="operator token">=</SPAN> <SPAN class="string token">"Stretch"</SPAN><SPAN class="punctuation token">;</SPAN>
rf1<SPAN class="punctuation token">.</SPAN>functionArguments&nbsp; <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"StretchType"</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="number token">6</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="comment token">//6 = PercentClip</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"MinPercent"</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="number token">0.5</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"MaxPercent"</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="number token">0.5</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"UseGamma"</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="keyword token">true</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"Gamma"</SPAN> <SPAN class="punctuation token">:</SPAN> <SPAN class="punctuation token">[</SPAN><SPAN class="number token">3.81464485861804</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3.81464485861804</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3.81464485861804</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"DRA"</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="keyword token">true</SPAN>
<SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> params1 <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">ImageServiceParameters</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
params1<SPAN class="punctuation token">.</SPAN>renderingRule <SPAN class="operator token">=</SPAN> rf1<SPAN class="punctuation token">;</SPAN>

<SPAN class="keyword token">var</SPAN> rasterLayer1 <SPAN class="operator token">=</SPAN>&nbsp; <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">ArcGISImageServiceLayer</SPAN><SPAN class="punctuation token">(</SPAN>url1<SPAN class="punctuation token">,</SPAN> <SPAN class="punctuation token">{</SPAN>imageServiceParameters<SPAN class="punctuation token">:</SPAN>params1<SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
map<SPAN class="punctuation token">.</SPAN><SPAN class="token function">addLayer</SPAN><SPAN class="punctuation token">(</SPAN>rasterLayer1<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>

<SPAN class="keyword token">var</SPAN> rf2 <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">RasterFunction</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
rf2<SPAN class="punctuation token">.</SPAN>functionName <SPAN class="operator token">=</SPAN> <SPAN class="string token">"Stretch"</SPAN><SPAN class="punctuation token">;</SPAN>
rf2<SPAN class="punctuation token">.</SPAN>functionArguments&nbsp; <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"StretchType"</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="number token">6</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="comment token">//6 = PercentClip</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"MinPercent"</SPAN><SPAN class="punctuation token">:</SPAN> <SPAN class="number token">0.5</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"MaxPercent"</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="number token">0.5</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"UseGamma"</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="keyword token">true</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"Gamma"</SPAN> <SPAN class="punctuation token">:</SPAN> <SPAN class="punctuation token">[</SPAN><SPAN class="number token">3.81464485861804</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3.81464485861804</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="number token">3.81464485861804</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp; <SPAN class="string token">"DRA"</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="keyword token">true</SPAN>
<SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> params2 <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">ImageServiceParameters</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
params2<SPAN class="punctuation token">.</SPAN>renderingRule <SPAN class="operator token">=</SPAN> rf2<SPAN class="punctuation token">;</SPAN>

<SPAN class="keyword token">var</SPAN> rasterLayer2 <SPAN class="operator token">=</SPAN>&nbsp; <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">ArcGISImageServiceLayer</SPAN><SPAN class="punctuation token">(</SPAN>url2<SPAN class="punctuation token">,</SPAN> <SPAN class="punctuation token">{</SPAN>imageServiceParameters<SPAN class="punctuation token">:</SPAN>params2<SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<SPAN class="keyword token">function</SPAN> <SPAN class="token function">executeLocal</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp; <SPAN class="keyword token">var</SPAN> rfLocal <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">RasterFunction</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp; rfLocal<SPAN class="punctuation token">.</SPAN>functionName <SPAN class="operator token">=</SPAN> <SPAN class="string token">"Local"</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp; rfLocal<SPAN class="punctuation token">.</SPAN>variableName <SPAN class="operator token">=</SPAN> <SPAN class="string token">"Rasters"</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp; <SPAN class="comment token">//int (1 = Plus, 2 = Minus, 3 = Times, ..., 40 = Mean )</SPAN>
&nbsp;&nbsp; rfLocal<SPAN class="punctuation token">.</SPAN>functionArguments <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="string token">"Operation"</SPAN> <SPAN class="punctuation token">:</SPAN> <SPAN class="number token">40</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="string token">"Rasters"</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="punctuation token">[</SPAN>rf1<SPAN class="punctuation token">,</SPAN> rf2<SPAN class="punctuation token">]</SPAN>
&nbsp;&nbsp; <SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp; rasterLayer1<SPAN class="punctuation token">.</SPAN><SPAN class="token function">setRenderingRule</SPAN><SPAN class="punctuation token">(</SPAN>rfLocal<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="punctuation token">}</SPAN>‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍<SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>