topic Re: Merging rasters with one value and overlay. in ArcGIS Spatial Analyst Questions

Merging rasters with one value and overlay.

JoeHarris — Thu, 10 Jan 2013 13:02:50 GMT

Hi!
Im having some 10-15 rasters consisting of different soils which I want to be only one raster file. Im having some problems finding out how to proceed as the mosaic operators doesn´t seem to work. The values are just 1 where there this soil type occur, eg. gleysol - 1. The rest is no data. I was thinking about combining but I guess that since there are no data there output will be just no data even if there are data.

The soil rasters will be used as an input to a weighted overlay with other data, such as precipitation, so what I basically want is a raster from 1-10 ranking the most suitable layer for some crop production.

Cheers
Joe Harris

Re: Merging rasters with one value and overlay.

MarkBoucher — Thu, 10 Jan 2013 14:02:55 GMT

Are the rasters to be overlaid (all cover same area) or pieced together side by side?

Re: Merging rasters with one value and overlay.

JoeHarris — Thu, 10 Jan 2013 14:41:57 GMT

Are the rasters to be overlaid (all cover same area) or pieced together side by side?

Side by side with the raster with the highest value to overwrite the lower value, so to speak.

I solved it by running raster to polygon, merging them together, adding the wanted raster value to the attribute table and then back to raster again. There must be a less time consuming way. However I got the result I wanted...

Re: Merging rasters with one value and overlay.

MarkBoucher — Thu, 10 Jan 2013 15:18:37 GMT

You could use raster calculator to multiply each raster by a value and then mosaic the resulting rasters together. If this was a repeatable task, you can set up a Model Builder model to do this.

Re: Merging rasters with one value and overlay.

JoeHarris — Thu, 10 Jan 2013 15:39:30 GMT

How? I don´t quite understand.. Or I solved that one to, thank you!

Can you answer this question?

I have point shapefiles which I want to convert to raster. The problem is I am getting the value -32767-32767 instead of just one value, like 7 or 3 when doing the point to raster.

Re: Merging rasters with one value and overlay.

MarkBoucher — Thu, 10 Jan 2013 17:07:23 GMT

If you have Spatial Analyst (SA), there is a tool called raster calculator. You can add it to the SA toolbar and then use it to perform basic raster math such as multiplying a raster by a constant, adding rasters together, preforming if/then functionality on rasters.

Model Builder is included in ArcMap and can be used to put together visual "macro". That is, you can drag and drop data from your mxd and tools from the toolbox into a model. Then, like a flow chart, you can connect them, change settings in the tools, define where you want the output to be saved, and run the model. In multi-step processes it works to both document the process and revise the process if at first you don't succeed.

Hope this helps.

Re: Merging rasters with one value and overlay.

curtvprice — Fri, 11 Jan 2013 04:32:09 GMT

Hi!
Im having some 10-15 rasters consisting of different soils which I want to be only one raster file. Im having some problems finding out how to proceed as the mosaic operators doesn´t seem to work. The values are just 1 where there this soil type occur, eg. gleysol - 1. The rest is no data.

The Cell Statistics Tool calculates stats cell by cell stats across a list of rasters. The MAXIMUM option for that tool sounds like what you're looking for. Be sure and check the box to ignore NODATA cells and the cells that have a NODATA in the stack will still come through to the output, as long as there is a data cell in the stack of inputs.