topic Re: Converting Raster Data Typ in Data Management Questions

Converting Raster Data Typ

JonasDanner — Thu, 01 Mar 2018 15:44:37 GMT

Good day,

I'm using an external Toolbox in my current analysis. One of the inputs has to be a short integer grid, containing values of "0" and "1". But the field type of the Raster I currently have (Tif-Format) is a long integer. I already tried to add a short integer field in the attribute table and used the field calculation. But the Input raster for the toolbox can not have another column then the short integer value. If I use the tool "delete field" to delete the long integer field, the geographical information gets lost, as this is the main value field. Do you know how I can convert the long into short integer values, od how can I create a new raster with short integer values?

Thanks in advance,

Jonas

Re: Converting Raster Data Typ

XanderBakker — Thu, 01 Mar 2018 16:09:57 GMT

If you have Desktop (ArcMap or ArcGIS Pro) and the Spatial Analyst extension you could use the Raster Calculator—Help | ArcGIS Desktop , and calculate something like this :

Con("YourRaster" == 1, 1, 0)‍

If you point the output to a TIF file, it will create an 8 bit unsigned integer:

You can't change the field type of the value field of a raster, since this is defined by the raster type.

Re: Converting Raster Data Typ

SteveLynch — Thu, 01 Mar 2018 16:18:39 GMT

use CopyRaster

Re: Converting Raster Data Typ

JonasDanner — Thu, 01 Mar 2018 16:29:49 GMT

ok, thank you! That means, if I have to have a short integer grid as Input, it can't be a Tiff-raster, but has to be something else?

Re: Converting Raster Data Typ

SteveLynch — Thu, 01 Mar 2018 16:37:07 GMT

No, the new output raster can be any format that supports short int. You decide on the Pixel type.

Re: Converting Raster Data Typ

JonasDanner — Thu, 01 Mar 2018 17:02:37 GMT

hm, I don't really understand it ... I open copy raster, Input raster is my 8-bit signed, long-integer tiff-raster. I name the output raster dataset "myraster.tif". I choose 4 bit. It executes and loads the result into the dataset. but when I'm checking the properties of the new raster it's 8-bit unsigned. and if I check the field properties in my attribut table it still says Type: Long

Re: Converting Raster Data Typ

SteveLynch — Thu, 01 Mar 2018 17:11:49 GMT

Are the values in your input raster in the 4 bit range?

Re: Converting Raster Data Typ

JonasDanner — Thu, 01 Mar 2018 17:33:48 GMT

I forgot that it was not only my values, but also a "count"-column, thats why... so I trid it again, now its a 4 bit unsigned raster. but still, the field properties in my attribut table is Type: Long... that's what I have to change

Re: Converting Raster Data Typ

SteveLynch — Thu, 01 Mar 2018 17:44:14 GMT

Only way that (I can think of) to do that is to add a short field to the table and then use CalculateField to update the values. To get this newly created field as the primary value field you’ll need to use the Lookup<http://desktop.arcgis.com/en/arcmap/10.3/tools/spatial-analyst-toolbox/lookup.htm> tool.

Re: Converting Raster Data Typ

JonasDanner — Thu, 01 Mar 2018 18:06:16 GMT

Thank you very much for your help! But sadly that doesn't work, as the lookup tool makes it a long-integer again...

Re: Converting Raster Data Typ

JonasDanner — Fri, 02 Mar 2018 11:48:40 GMT

Update: I think it should also work with a 4bit long-integer value grid. So thank you very much. The toolbox still returns errors. Sadly I don't have an explanation of the error codes, thats why I thought the short-integer/long-integer would be the problem, as the description demands a short-integer grid

But: im processing this file with my DTM. I clipped both rasters, the DTM and the integer grid with the same polygone-shapefile. To be able to process them, they have to be the same extent. But if I compare both clipped results, the both have the same pixel size (5, 5) and the same number of rows (4949), but the number of columns varies by one (4539 and 4538). I think is is causing my error. But I don't know how to adjust them, I also clipped the bigger one (with 4539 columns) and used the smaller one as the output extent. but the result still had 4539 columns...

Do you know another way I could try to cut them the same size?

Re: Converting Raster Data Typ

JonasDanner — Fri, 02 Mar 2018 11:57:59 GMT

It Didn't work with clip, but with extract by mask. So hope the toolbox works now. thank you very much to you!