topic Re: Updating a subset of raster values using ArcMap in ArcMap Questions

Updating a subset of raster values using ArcMap

ManishShrivastav — Thu, 17 Jun 2021 20:05:31 GMT

I have a source raster data set (tif file) I want to select a subset (cells) of the source raster data, change the values of the selected cells and write the changes values again to the source raster.

How should I approach this in ArcMap.

Thank you,

Manish

Re: Updating a subset of raster values using ArcMap

JayantaPoddar — Thu, 17 Jun 2021 20:08:57 GMT

Subset by an area of interest (polygon) or by a range of values?

Re: Updating a subset of raster values using ArcMap

ManishShrivastav — Thu, 17 Jun 2021 20:20:53 GMT

By Area of interest.

Re: Updating a subset of raster values using ArcMap

JayantaPoddar — Thu, 17 Jun 2021 20:29:28 GMT

1. Convert the Polygon to Raster . Keep the cell size same as the source raster. Also define snap Raster (Environment) as the source Raster.

2. Use Raster Calculator with a similar expression.

Con(IsNull("Raster2.tif"), "Raster1.tif", 0)

replace "Raster1.tif" with the source Raster name

Raster2.tif with the subset raster name

and replace 0 with the desired constant value

Re: Updating a subset of raster values using ArcMap

ManishShrivastav — Fri, 18 Jun 2021 02:14:28 GMT

Thanks a lot, this worked for me partially. But this creates a new raster masked by the polygon area, my need is that the changes should be made to the selected subset of cells in the original raster and get back the original raster along with the changed values such that the area that were not under the polygon should remain unchanged.

Re: Updating a subset of raster values using ArcMap

JayantaPoddar — Fri, 18 Jun 2021 02:53:12 GMT

Raster tools will usually create a new output. Use the above tools in a model builder along with Copy and Delete tools.

*Keep a backup of your source raster before executing the workflow, since the Delete is permanent.

What value do you want to put for pixels falling in the subset area? What other deviation are you seeing from your desired result?