topic Re: How to intersect two rasters in ArcGIS Spatial Analyst Questions

How to intersect two rasters

ErikFernandez — Thu, 23 Jul 2015 17:12:17 GMT

I'm very familiar with using the intersect tool with shapefiles/geodatabases. I have two rasters that I'd like to do the same with. It would be super helpful if someone could point me toward a tool that would do this. Basically, raster 1 has values ranging from 1-10 and raster 2 has values ranging from A-E. I want to be able to create a new raster that tells me for example how many acres have a value of 1 that overlap with value A. Any suggestions are much appreciated!

Erik

Re: How to intersect two rasters

michaelcollins1 — Thu, 23 Jul 2015 17:25:16 GMT

You could either convert both rasters to shape files and do an intersect, or be a little creative with raster math. Resample the second raster to values in increments of 25 say, and then add the 2 rasters together. The "intersect " would be raster values 26, 51, 76, etc.

Re: How to intersect two rasters

DarrenWiens2 — Thu, 23 Jul 2015 17:42:39 GMT

I believe Tabulate Area will do this for you.

Re: How to intersect two rasters

XanderBakker — Thu, 23 Jul 2015 19:17:33 GMT

If Tabulate Areas doesn't yield the format you require and each combination needs to be on a single record, you can use Combine—Help | ArcGIS for Desktop . This will yield a new raster with the combinations and the attribute table can be used to define the areas (count * pixelsize)

Re: How to intersect two rasters

ErikFernandez — Thu, 23 Jul 2015 21:57:26 GMT

hmmm, the suggestions are close but not exactly the right fit for what I'm trying to do (or it's possible I'm not understanding the suggested tools).

- I tried converting to a shape file and intersecting. Files are too big, never finishes.

- Here's a more thorough explanation of what I'm trying to do. Grid 1 represents all of the counties in Oregon, about 30. Grid two represents a range of values corresponding to how much biomass is stored per acre. I am trying to figure out how much biomass is stored in each county.

- With regard to tabulate area - if you look at the illustration at the link provided above, what I'd like to calculate is for example to look at all of the boxes with 1 as the value in the left box and know what the total values added up in the corresponding 2nd box are that have a 1 in the first box. So the final table would have a field for value, and the first record would be 1 and the the second field would be total and would equal 55. Above real example might be easier to follow.

Again, thank you for the suggestions.

Re: How to intersect two rasters

DarrenWiens2 — Thu, 23 Jul 2015 22:03:58 GMT

In that case, quite different description than the original btw, you should look into Zonal Statistics, SUM. You may find it easier to create a new raster with absolute values of biomass per pixel, rather than adding biomass per acre, but it's up to you.