7 replies to this topic

[daak9193]

Might be a stupid question but how do i take a tiff and transform the different collors to layers.

 

I used reclassify on the raster to make the 13 different classes i wanted but I dont think it worked well.

 

Is their a better way to somehow split the raster in to the 13 different layers i want based on what collour they have?

[Dennis McClendon]

In Photoshop, you can select the pixels by color, cut them, and then paste them into a different layer or file.

[frax]

What software are you using?

[daak9193]

I always forget to say what software Im using. I use arcmap 10.1

[frax]

Assuming you have spatial analyst, it is very easy to create a model (model builder) or a simple python script to separate the different classes. You basically have to run the SetNull map algebra 13 times.

[daak9193]

hmm I might look stupid asking this but one of the collors got the RGB values  Blue: 27 G:142 R: 229. I use setnull to Value = 229 and then i get a raster with "stretched" collor ramp and the collor i want get value 0. SO far so good.

 

 How do i extract that collor to a separate layer so i then can make that in to a polygon?   Does my question make any sense?

[AndrewM]

If you just want to extract each different colour as a polygon then you should be able to go to 'conversion tools' in the toolboxes section and then expand the 'from raster' tab and choose 'from raster to polygon'. That will then create a polygon layer with a polygon for each of the raster classes - i.e. each different colour.

 

You can then select each polygon by its attributes and export them to separate layers if you need to - this may be easier than creating the separate raster layers first and then converting them to polygons.

[frax]

Copy the tiff to an ArcInfo raster/grid - then you get a stack with separate r/g/b layers (in a stack). Just use one of those where all the 13 classes are differentiated.