topic Re: The NDVI Python function doesn't provide any output in ArcGIS Pro Questions

The NDVI Python function doesn't provide any output

MaryamBarzegar — Thu, 21 Oct 2021 23:39:15 GMT

Hi, does the NDVI Python function actually work? It doesn't retrieve any output for me.

https://pro.arcgis.com/en/pro-app/2.7/arcpy/image-analyst/ndvi.htm

Re: The NDVI Python function doesn't provide any output

JayantaPoddar — Fri, 22 Oct 2021 00:01:42 GMT

If you are using a standalone python script, you could use a similar script as the following

# Import system modules import arcpy from arcpy.ia import * # Set the analysis environments arcpy.env.workspace = "C:/arcpyExamples/data" # Set the local variables in_raster = "landsat8.tif" # Execute NDVI function out_ndvi_raster = NDVI(in_raster, 5, 4) # Save the output out_ndvi_raster.save("C:/arcpyExamples/outputs/NDVI.tif")

Re: The NDVI Python function doesn't provide any output

DanPatterson — Fri, 22 Oct 2021 00:09:56 GMT

Did you save the raster?

Raster—ArcGIS Pro | Documentation

by "retrieve " do you mean it doesn't create one, or you don't see one?

Re: The NDVI Python function doesn't provide any output

MaryamBarzegar — Fri, 22 Oct 2021 00:19:44 GMT

Thank you @JayantaPoddar and @DanPatterson but I saved the raster and I have exactly the same code but it doesn't produce anything and I don't get any errors either. Does this work with any satellite image? Mine is WorldView 2

Re: The NDVI Python function doesn't provide any output

JayantaPoddar — Fri, 22 Oct 2021 00:43:18 GMT

I assume you have Image Analyst Extension for ArcGIS Pro.

Bands are different for WorldView 2.

Maybe you could try Band 7 (NIR1) and Band 5 (Red).

Also ensure you are providing an existing workspace which contains the composite image (containing multiple bands), the correct image name and existing output path.

If you still have confusion, please share the screenshot of the folder containing the Worldview 2 image(s) in Windows Explorer, and also the script you have so far.

Re: The NDVI Python function doesn't provide any output

MaryamBarzegar — Fri, 22 Oct 2021 03:35:06 GMT

Are you sure I need Image Analyst extension? Raster functions don't need Image Analyst extension. When I use the NDVI tool, I can create an NDVI image and I don't have Image Analyst extension. Also, I think at least it needs to give me an error if Image Analyst extension is the issue

Re: The NDVI Python function doesn't provide any output

DanPatterson — Fri, 22 Oct 2021 09:10:05 GMT

it appears elsewhere other than the IA

NDVI function—ArcGIS Pro | Documentation

An overview of the Spatial Analyst functions—ArcGIS Pro | Documentation