Can the maximum and minimum values of raster display be changed automatically when changing the data frame extents?

Question

I have a raster layer in arcgis which covers a large surface area. I would like to be able to zoom into specific areas of this raster and have it display only the range of values in the area I have zoomed to. Is this possible?

For example if the range of values for the entire raster is 0-255 but the range of values at the current extent is only 25-100 I would like the symbology to represent only those values between 25-100, until I zoom to a different scale.

Answer 1

You can accomplish this with multiple layers pointing to the same raster source. Give each layer its own separate scale range and symbology.

If you wanted to have a particular symbology between 1:25 and 1:100, you'd set those values on the General tab as shown below. Then choose the appropriate symbology on the Symbology tab.

Then you might have, say, two additional layers: one covering 1:1 - 1:24, and one covering 1:101 - 1:255.

Answer 2

Try this out:

import arcpy, os, traceback, sys
from arcpy import env
env.workspace="in_memory"
env.overwriteOutput = True

try:
    def showPyMessage():
        arcpy.AddMessage(str(time.ctime()) + " - " + message)
    mxd = arcpy.mapping.MapDocument("CURRENT")
    color_layer=arcpy.mapping.ListLayers(mxd,"silver.tif")[0]
    wholeRaster=arcpy.Raster(color_layer.dataSource)
    df = arcpy.mapping.ListDataFrames(mxd)[0]
    ext=df.extent
    ext='%s %s %s %s' %(ext.XMin, ext.YMin,ext.XMax,ext.YMax)
    arcpy.Clip_management (wholeRaster, ext, "victim")
    desc = arcpy.GetRasterProperties_management("victim", "MINIMUM")
    minV = int(desc.getOutput(0))
    desc = arcpy.GetRasterProperties_management("victim", "MAXIMUM")
    maxV = int(desc.getOutput(0))
    arcpy.AddMessage('%s %s' %(minV,maxV))
    intervals=5; valueList=[]
    dV=(maxV-minV)/intervals
    for i in range(intervals+1):
        valueList.append(minV+int(dV*i))
    color_layer.symbology.valueField="Value"
    color_layer.symbology.classBreakValues =valueList
    arcpy.RefreshActiveView()
    arcpy.RefreshTOC()
except:
    message = "\n*** PYTHON ERRORS *** "; showPyMessage()
    message = "Python Traceback Info: " + traceback.format_tb(sys.exc_info()[2])[0]; showPyMessage()
    message = "Python Error Info: " +  str(sys.exc_type)+ ": " + str(sys.exc_value) + "\n"; showPyMessage()