NDVI in GRASS GIS

May 26, 2024 | GRASS

“Hey you’ve been on a NDVI kick as of late!”. Technically I’ve been on a learning kick as of late. When I get burned out I tend to float back to the thing that gives me some comfort and that’s numbers and mapping etc.

This morning (being a Holiday weekend) I decided to tackle NDVI in GRASS. I don’t know if you’ve fired up GRASS lately but it’s different. Different in a good way.

One interface and not a series of menus. Processing tools on the right. Map layers on the left.

So – how do I get an NDVI map out of this? I have the USGS NAIP with it’s four bands. So lets use r.in.gdal to import my raster. That’s going to give me a 4 band import.

Once that’s done a lot of things get set like region and resolution. If you remember – (or at least as I remember) that was a manual process. So you end with with 4 bands displayed in the view. That’s boring. Lets skip to the chase and use i.vi.

Aaaaannnnnndd with a click of the run button it’s done. That is it. You also get the python from the tool.

i.vi --overwrite output=NDVI viname=ndvi red=m_3408418_se_16_060_20220110.1@PERMANENT nir=m_3408418_se_16_060_20220110.4@PERMANENT green=m_3408418_se_16_060_20220110.2@PERMANENT blue=m_3408418_se_16_060_20220110.3@PERMANENT

Here you go:

I know there’s more that I can do at this point and I probably will when I take another break and dig into some common problems and tackling it with a different toolset.

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