[GIS] Error in raster displays of NoData cells when “zoomed in” past scale 1:3,000,000

arcgis-10.2arcgis-desktopdisplayrasterscale

I have encountered an error in how ArcGIS Desktop displays a Raster file (.TIF format) at different scales. At scales greater than 1:3,76,600, when I'm zoomed in, the raster displays mostly correctly, showing only a border of low-value cells, or no border -the "border" appears inconsistently. (first picture)

enter image description here

What is consistent is that when I zoom out, specifically when I go from 1: 3,000,000 to 1:4,000,000, the white background (correctly indicating no-data cells) change to blue (indicating the lowest value "bin" in the classification). When I check the cell values, the cells are NoData value, even when zoomed in and blue (and they should be clear). (second picture)

enter image description here

Any suggestions?

I want to display this data zoomed out to a scale smaller than 1:3,000,000 but it is falsely visualizing the data. I am working in ArcGIS Desktop 10.2 with all licenses installed. In Layer Properties > General Tab > "Scale Range," "Show layer at all scales" is checked.

Best Answer

I sometimes encounter similar errors, especially if the raster values repesent some non-continuous data (like classifications). This is probably related to pyramids which seem to not fully respect nodata values in some cases.

There are two possible workarounds:

Rebuild the pyramids of your raster data. For classification rasters, you should use Nearest Neighbor technique (interpolating makes no sense there). You can also clear the pyramids (i.e. set pyramid level to 0) if re-building pyramids has no effect. The raster is then displayed without pyramids - this may slow down its display depending on your raster size. For small rasters, you may well go without pyramids. (I tend to turn off pyramids for classification rasters)
Manually assign a display color of your NoData value for each raster image.

Related Solutions

Raster – Filling Gaps in Raster to Zero Value Cells

I believe that your "gaps" are, in fact, NoData. The rule in raster operators is that NoData begets NoData. You can use the raster calculator and a nested statement, without the use of the constant raster, to set NoData to 0. Depending on the version of ArcMap you may need to play with syntax but the basic idea is:

Con(IsNull("raster"), 0, "raster")

This states that if the raster is NoData then assign the new raster 0 else keep the value of the original raster.

[GIS] Setting NoData for a multiband raster

What you want to do is Set Raster Properties in a script or change it manually in ArcCatalog. This will not create a new raster or even take very long.

In python it's a bit tricky:

import sys, os, arcpy

InFolder = sys.argv[1]
arcpy.env.workspace = InFolder

for Ras in arcpy.ListRasters():
    arcpy.AddMessage("Processing " + Ras)
    arcpy.SetRasterProperties_management(Ras,nodata="1 0;2 0;3 0")

Because the nodata is way down the list I find it easier to specify that; the parameters are Band Value;Band Value;... until all the bands are addressed. If you are likely to have more bands (or less) in the same folder then you will have to use arcpy.Describe and the bandCount property to set the null for the correct number of bands:

import sys, os, arcpy

InFolder = sys.argv[1]
arcpy.env.workspace = InFolder

for Ras in arcpy.ListRasters():
    arcpy.AddMessage("Processing " + Ras)
    desc = arcpy.Describe(Ras)
    if desc.bandCount == 3:
        arcpy.SetRasterProperties_management(Ras,nodata="1 0;2 0;3 0")
    elif desc.bandCount == 4:
        arcpy.SetRasterProperties_management(Ras,nodata="1 0;2 0;3 0;4 0")
    elif desc.bandCount == 1:
        arcpy.SetRasterProperties_management(Ras,nodata="1 0")

In ArcCatalog, right click on the layer and go to properties: enter image description here

hit the edit button:

enter image description here

Enter the values then hit OK to dismiss the NoData editor and OK to enforce the change.

Now the raster will display nothing in ArcMap where the cell value is 0,0,0.

Best Answer

Related Solutions

Raster – Filling Gaps in Raster to Zero Value Cells

[GIS] Setting NoData for a multiband raster

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