topic Re: Add several raster files (ecw) from one folder, Symbology RGB in Python Questions

Add several raster files (ecw) from one folder, Symbology RGB

SilvanStöckli — Sat, 11 Dec 2021 17:48:21 GMT

Hello

I'd like to add several raster files (format: .ecw) from one folder with several subfolders to my mxd-file. It works fine with the following code:

workspace = r"C:\Workspace"   #Workspace
... 
... 
... #Code
... import arcpy, os
... 
... mxd = arcpy.mapping.MapDocument("CURRENT")
... df = arcpy.mapping.ListDataFrames(mxd, "*")[0]
... 
... walk = arcpy.da.Walk(workspace)
... 
... for dirpath, dirnames, filenames in walk:
...     for filename in filenames:
...         arcpy.mapping.AddLayer(df, arcpy.mapping.Layer(os.path.join(dirpath, filename)))

The Problem is, that after adding them like this, they appear with a symbology "stretched values along a color ramp" but they should be drawn as "RGB composite".

Can someone help me?

Re: Add several raster files (ecw) from one folder, Symbology RGB

DanPatterson_Retired — Thu, 16 Jun 2016 12:44:34 GMT

I can find nothing but read-only properties Layer—Help | ArcGIS for Desktop in the arcpy.mapping module. I presume that is because histograms and band statistics are required for multiband rasters. All other references to rasters and symbology refer to setting a raster's symbology to an existing layer file (lyr) which isn't going to work in your case

http: //desktop.arcgis.com/en/arcmap/latest/analyze/arcpy-mapping/layer-class.htm

Re: Add several raster files (ecw) from one folder, Symbology RGB

SilvanStöckli — Thu, 16 Jun 2016 13:02:20 GMT

Thanks for your help.

I can't open the Link. May you post it again?

Would that mean that there's a option I could set?

I don't mind setting the symbology afterwords but I couln't figure a way to do so.

Re: Add several raster files (ecw) from one folder, Symbology RGB

DanPatterson_Retired — Thu, 16 Jun 2016 13:54:45 GMT

I copied the link as text above

Timothy Hales check my link above... I just copied and pasted the url and this error keeps appearing. I have seen this before

Re: Add several raster files (ecw) from one folder, Symbology RGB

TimothyHales — Thu, 16 Jun 2016 14:24:56 GMT

I thought it may be the dash, but this URL works:

http://desktop.arcgis.com/en/arcmap/latest/analyze/arcpy-classes/cursor.htm

However I noticed the URLs with two dashes do not:

http://desktop.arcgis.com/en/arcmap/latest/analyze/arcpy-mapping/styleitem-class.htm

I have an open case with Jive Software to determine the issue. Thanks for letting me know!

Re: Add several raster files (ecw) from one folder, Symbology RGB

SilvanStöckli — Fri, 17 Jun 2016 07:48:11 GMT

so does this mean that there's no solution for my problem?

Re: Add several raster files (ecw) from one folder, Symbology RGB

DanPatterson_Retired — Fri, 17 Jun 2016 07:55:58 GMT

If you managed to get through to the link by a manual search on the topic, you would see that there is no arcpy access to that particular symbology probably because it is dependent on other things which may not exist. The rest of the discussion was directed toward the failure of a direct link to the help files not working.

To return to your issue... can you set the symbology to what you want manually? is not, does pyramids/histograms help do it manually?

Re: Add several raster files (ecw) from one folder, Symbology RGB

andrewj_ca — Mon, 20 Jun 2016 18:28:15 GMT

Hi Silvan,

Have you considered starting with a Raster Mosaic?

Mosaic—Data Management toolbox | ArcGIS for Desktop

Re: Add several raster files (ecw) from one folder, Symbology RGB

SilvanStöckli — Tue, 21 Jun 2016 07:52:44 GMT

Yes, I can set the symbology manually. But I'll have to do so for about 100 Rasters, which really sucks. And I'll have to do it at least once a year.

I tried to use a Raster Catalog. But this enlarged the Data (from 8G to 130G) and was extremely slow.

I can't create a MosaicDataset because I run on basic licence.

Re: Add several raster files (ecw) from one folder, Symbology RGB

SilvanStöckli — Tue, 21 Jun 2016 14:44:49 GMT

Ok, I solved it diffrently:

I made a Batch-Script:

for /R C:/Path %%f in (*.ec*) do copy %%f C:/Path2/

So now I copy all the files from the folder with those many subfolders to one single folder.

It works fine. The only sad thing is that I now do have two folders with all those images... but still much better than doing all this manually...

If someone knows about an other method without copying the files, I would still be interested in the solution.

Re: Add several raster files (ecw) from one folder, Symbology RGB

Luke_Pinner — Sat, 11 Dec 2021 17:48:23 GMT

I got it to work by adding the ECWs, then updating the stretched layer using a template RGB .lyr file:

import os

workspace = r"C:\Temp\Test"  #Workspace 
rgb_lyr = arcpy.mapping.Layer(r"C:\Temp\rgb.lyr")

mxd = arcpy.mapping.MapDocument("CURRENT") 
df = mxd.activeDataFrame

walk = arcpy.da.Walk(workspace) 

for dirpath, dirnames, filenames in walk: 
    for filename in filenames: 
        print os.path.join(dirpath, filename)
        lyr = arcpy.mapping.Layer(os.path.join(dirpath, filename))
        arcpy.mapping.AddLayer(df, lyr) 
        updateLayer = arcpy.mapping.ListLayers(mxd, lyr.name, df)[0]
        arcpy.mapping.UpdateLayer(df, updateLayer, rgb_lyr)

You could also use replaceDatasource on the template layer:

import os

workspace = r"C:\Temp\Test"   #Workspace  
rgb_lyr = r"C:\Temp\rgb.lyr"

mxd = arcpy.mapping.MapDocument("CURRENT")  
df = mxd.activeDataFrame
  
walk = arcpy.da.Walk(workspace)  
  
for dirpath, dirnames, filenames in walk:  
    for filename in filenames:  
        lyr = arcpy.mapping.Layer(rgb_lyr)
        lyr.replaceDataSource (dirpath, 'RASTER_WORKSPACE', filename)
        lyr.name = filename
        arcpy.mapping.AddLayer(df, lyr)

Re: Add several raster files (ecw) from one folder, Symbology RGB

SilvanStöckli — Mon, 27 Jun 2016 06:24:39 GMT

that's perfect!

Thanks a lot! 😄