topic Re: Arcpy clip file tiff in Python Questions

Arcpy clip file tiff

DEVAPP — Wed, 21 Sep 2016 21:03:15 GMT

Hi guys,

i have a tiff image that into Arcmap i clip with Data Frame Clip using a shp file into data frame as mask to clip and i have the result that you can see into this image

instead when i create a python script i can't use clip data frame so i use clip_managment or extract by mask with the same shp file but the result is different, you can see in this second image

You can see that the bouds of clip are not smooth as first clip resulted by clip data frame.

How i can resolve this problem and have the same result with bounds smooth?

Thanks

Re: Arcpy clip file tiff

DanPatterson_Retired — Wed, 21 Sep 2016 21:08:44 GMT

in order to get the smoother edge, you have to explicitly set the cell size in the Environments tab of the tool. If you don't, it defaults to 1/250th of the maximum of the extent with or height. So when opening any tool in Arctoolbox, the first place you should go to is the Environments Tab and set your raster properties (there are a couple of places inside)

Re: Arcpy clip file tiff

DEVAPP — Wed, 21 Sep 2016 21:22:23 GMT

Ok but i have deelop a script to add into custom toolbox

Re: Arcpy clip file tiff

DanPatterson_Retired — Wed, 21 Sep 2016 21:38:14 GMT

would be nice to mention that as well, but as usual, there is an arcpy interface... see the examples in Environments section of arcpy and those that apply to raster processing.

Cell Size (Environment setting)—Help | ArcGIS for Desktop

Re: Arcpy clip file tiff

DEVAPP — Wed, 21 Sep 2016 22:26:15 GMT

Dan i have set arcpy.env.cellSIze = 0.5 and after i have run my arcoy clip but the result is the same. More bounds are not smooth

Re: Arcpy clip file tiff

DanPatterson_Retired — Wed, 21 Sep 2016 22:49:27 GMT

If you have a script, you should post it... it is not possible to discern an error from comments solely

Re: Arcpy clip file tiff

DEVAPP — Thu, 22 Sep 2016 08:04:32 GMT

Hi Dan this is my script

def main():
    print "Start script"
    arcpy.env.overwriteOutput=True
    arcpy.env.cellSize = 0.1
    env.workspace = arcpy.GetParameterAsText(0)
    date = arcpy.GetParameterAsText(1)
    excludedValues = arcpy.GetParameterAsText(2)
    mxd = arcpy.mapping.MapDocument("Map.mxd")
    df = arcpy.mapping.ListDataFrames(mxd, "Layers")[0]
    strNdvi = "ndvi.tif"
    strNdviLayer = "ndviLayer.lyr"
    Temp_Symbology = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'ndviLayer.lyr')

    # Generate NDVI
    strRedImage = "Image1.jp2"
    strIVImage = "Image2.jp2"
    strPolygons = "polygon.shp"
    strPolygon = "polygon"
    sr = arcpy.Describe(strRedImage).spatialReference
    df.spatialReference = sr

    if not arcpy.Exists(strNdvi) and arcpy.Exists(strRedImage) and arcpy.Exists(strIVImage):
        rasNdvi = Divide(Minus(Float(strRedImage),Float(strIVImage)),Plus(Float(strRedImage),Float(strIVImage)))
        rasNdvi.save("ndvi.tif")
        print "NDVI created."

the ndvi created have a cell size 10 x 10 , i have used Describe to see

and this is the rest of code

arcpy.MakeRasterLayer_management(strNdvi, "ndvilyr")
    lyrNdvi = arcpy.mapping.Layer(strNdvi)
    arcpy.mapping.AddLayer(df, lyrNdvi)
    lyr = arcpy.mapping.ListLayers(mxd)[0]

    ##Clip Raster Dataset with feature geometry
    arcpy.env.cellSize = 0.05
    arcpy.Clip_management("ndvi.tif", "#", "ndvi_clip.tif",strPolygons, "0", "ClippingGeometry")
    print "clip ok"

and the result is the second image, with bounds not smooth

thanks

Re: Arcpy clip file tiff

DanPatterson_Retired — Thu, 22 Sep 2016 09:48:36 GMT

Make Raster Layer—Help | ArcGIS for Desktop doesn't honour global settings other than workspaces... try

Feature to Raster—Help | ArcGIS for Desktop which uses a cell size explicitly

You have to check what environment variables are honoured by tools as well

Re: Arcpy clip file tiff

DEVAPP — Thu, 22 Sep 2016 10:02:46 GMT

Hi have try Dan but the result is always the same.

I have a result clip with bounds not smooth

Re: Arcpy clip file tiff

DanPatterson_Retired — Thu, 22 Sep 2016 11:41:01 GMT

you set the cell size in FeatureToRaster?

Re: Arcpy clip file tiff

DEVAPP — Thu, 22 Sep 2016 12:11:57 GMT

Yes i have set 0.5 cellsize but the result is always the same. I have try to set into env cellsize value 0.5 and run replace with this value as cell size but result is always the same

The bounds are not smooth

Re: Arcpy clip file tiff

DanPatterson_Retired — Thu, 22 Sep 2016 16:47:13 GMT

skip the script for now... do the process manually using the tools in arctoolbox, when it works, go to Customize, Results and copy and paste the results of the process and export to a python code snippet so that we can see what was a 'successful' run to narrow down what your code situation problem is.

Re: Arcpy clip file tiff

DEVAPP — Sun, 25 Sep 2016 08:14:31 GMT

Hi Dan,

thank for your help.

I have change the workflow into script and now works fine. Problem was the first clip of raster before resample.

I have try to clip the raster with a big polygon and after run the resample but with cell size 0,5 and. After i have execute other clip on resample result with a smal shp and the ruslt is good.

Now i have see other some strange but i will post it in other question