topic Re: Combining non-overlapping rasters without any changes to cell data in ArcGIS Pro Questions

Combining non-overlapping rasters without any changes to cell data

Garjel_blah — Mon, 15 Jan 2024 01:52:26 GMT

Hello, I'm fairly new to ArcGIS Pro, and I'm having a lot of trouble with something that I expected be fairly simple, so forgive me if I've overlooked something obvious.

I'm trying to create a 250m resolution soil raster map of the UK, but I can only download this data in individual 2x2 degree tile TIFFs. It takes 21 such tiles to cover the UK. I now want to use ArcGIS Pro to combine these separate rasters into a single layer or TIFF, so that future operations can be done once instead of 21 separate times. I don't want to change the soil data in each cell, I just want all of the data to be grouped into a single raster layer instead of 21 separate ones.

I've tried this with several tools. With Raster Calculator and Combine I have only succeeded at creating empty rasters that do not appear on the map and have no rows in their attribute tables. With Mosaic to New Raster I have managed to create a viable raster, but this tool has a frustrating tendence to slightly alter the soil values. I can tell because the maximum value of the combined raster is less than the maximum value of the separate rasters. I have tried each of the mosaic operators and resampling techniques, but so far it has been impossible to preserve the exact soil data.

Are there any options I haven't tried yet? Or is some error inevitable when combining rasters? I may end up doing it in Python.

Re: Combining non-overlapping rasters without any changes to cell data

DanPatterson — Mon, 15 Jan 2024 02:24:12 GMT

Have you considered creating a mosaic dataset?

Mosaic datasets—ArcGIS Pro | Documentation

or for simpler ideas

Mosaic To New Raster (Data Management)—ArcGIS Pro | Documentation

with more options

Mosaic (Data Management)—ArcGIS Pro | Documentation

Re: Combining non-overlapping rasters without any changes to cell data

Luke_Pinner — Mon, 15 Jan 2024 07:10:46 GMT

Mosaic to New Raster doesn't alter cell values (unless there's a need to resample, and it sounds like there is no need for your tiles). You are just seeing approximate statistics. Add the mosaiced raster and the original tiles, turn them on and click anywhere using the explore tool to get a popup showing raster values where you clicked and you'll see they're the same.