idea Raster function to highlight water in near-infrared ortho in ArcGIS Pro Ideas

Raster function to highlight water in near-infrared ortho

Bud — Wed, 16 Jul 2025 02:10:16 GMT

I have a 4-band ortho with near infrared in the fourth band. I've used the fourth band as red.

I know from being on site that there is a creek at the yellow line and some standing water at the white line. And I can see it in the ortho, too.

Using a raster function, I want to highlight the known waterbodies, as well as other unknown waterbodies, in a bright colour. I've tried using the NDVI raster function, but none of the NDVI options highlight the water. Only the vegetation seems to be pronounced in the output NDVI layers.

Can a raster function be added that can highlight water in a bright colour? I can send the .tif ortho file to Esri staff in a private message or email if needed.

Re: Raster function to highlight water in near-infrared ortho

BobBooth1 — Wed, 16 Jul 2025 18:11:19 GMT

Have you tried the NDWI raster function?

Re: Raster function to highlight water in near-infrared ortho

Bud — Thu, 17 Jul 2025 00:57:01 GMT

@BobBooth1 Thanks. I tried your suggestion, but the output layer doesn't seem to highlight water at all. If anything, the water is de-emphasized. Not sure why.

Re: Raster function to highlight water in near-infrared ortho

BobBooth1 — Thu, 17 Jul 2025 14:58:03 GMT

NDWI should highlight water. It may be that the band combination of inputs is wrong? The order of bands in rasters varies.

This tutorial has a notebook showing how to use raster calculations to make an NDWI output layer.

https://arcgis.com/home/item.html?id=24e13f2f4fe8453b9d1107e1f5b1d3cf

Re: Raster function to highlight water in near-infrared ortho - Status changed to: Closed

ValeriaChavez — Mon, 11 Aug 2025 18:20:24 GMT

Hi @Bud! What you're describing in your Idea should be possible with the Band Arithmetic raster function leveraging the NDWI method:

NDWI = (Green - NIR) / (Green + NIR)

If the results you're getting do not look as expected, I would encourage you to contact Technical Support.

Thank you for your continued engagement on Esri Community.