Converting Red to Blue Topography information into Grayscale

[Gander0]

Hi folks,

 

Title pretty much says it all.

 

I have a image with topographic data, red representing highest areas, through yellow, then cyan down to blue in lowest areas.

 

Does anyone have any ideas how to turn this into a greyscale in photoshop in order to displace a plane within a 3d App?

 

Have tried the Black and White adjustment layer, but the transitions don't really work and manually tweaking values is not proving very accurate.

 

Any help is much appreciated.

[jinsley]

can you post the image? could you use "median" filter to help define the areas and then just trace it out with splines to make your topo? How big is the site? How important is it that the site model is really accurate?

[Gander0]

Thanks for the reply jinsley,

 

This is all a bit of an experiment for me in order to avoid the taking the splines route.

 

To be honest my results aren't bad I was just wondering if there was an easy photo-shop solution I had overlooked as my by eye method is far from perfect. (Something like grayscaling along a specified colour gradient?)

[jinsley]

maybe not photoshop, but using illustrator you can trace some vector paths with the "live trace" option and export a dwg...

 

I got this really fast...

 

[ATTACH=CONFIG]37969[/ATTACH]

[Gander0]

Jinsley,

 

Cheers for looking further, that looks like a good option for the vector paths.

 

I was hoping however for a way to turn to the coloured image into a reasonably accurate gray scale image in order to use in vue.

 

Not to worry, I'm reasonably happy with my less accurate version for now.

 

Thanks again

[-MerlyN-]

Hm, I did a quick google search on the topic and it seems, that programs like ArcGIS and such are able to export RAW DEM data either into a colored profile like you've got here or a grayscale image for further processing. The easiest way it seems would be to ask your client for a grayscale export. Far from being an expert it doesnt seem to be possible to convert the colored image back to grayscale and keep the original elevation. It might be possible to do it manually though by converting each channel seperately and layer filter them back together, if you have the elevation table, but thats just a guess, and the aforementioned options work probably a lot faster...

[jinsley]

One last try, isolating the different channels and playing around in ps to get a 16 bit png

 

[ATTACH=CONFIG]37970[/ATTACH]

[jinsley]

Nils, you read my mind...

[Gander0]

Jinsley,

 

Thanks for your time! Those channel tweaks are similar to what I did to achieve the terrain attached previously. It works well but probably not that accurate.

 

MerlyN,

 

Thanks for your reply. No client on this one, just experimenting with data found online. Will have a look into that software you suggested.

[mitchellpeacock]

I use MapInfo with Vertical Mapper. I usually generate the blue>red topo maps from xyz data. It might be possible that I can also read them back in (never needed to try it before) and export a mesh in dxf format. Will have a look later.

 

If you are just experimenting though, I have plenty of ascii xyz data you can play with for areas up to 10x10 km. (there is a plugin called dem2max which reads the ascii files)

[mitchellpeacock]

From the help file - it looks possible. Ideally, I guess it would need to be georeferenced so you would need to know the tl & br grid refs so the scale would be correct.

[ATTACH]37992[/ATTACH]

 

Looks like it might be a bit of a *** assigning the colours to corresponding heights. Easiest option would be to get hold of the original DEM data - creating a mesh from DEM data literally takes minutes either in max or mapinfo.

[-MerlyN-]

From the help file - it looks possible. Ideally, I guess it would need to be georeferenced so you would need to know the tl & br grid refs so the scale would be correct.

[ATTACH]37992[/ATTACH]

 

Looks like it might be a bit of a *** assigning the colours to corresponding heights. Easiest option would be to get hold of the original DEM data - creating a mesh from DEM data literally takes minutes either in max or mapinfo.

 

That was exactly, what I meant when I said you need the color table and that all other options would be faster.

[Gander0]

Thanks for the info and the offer of data Mitch.

 

I'm playing around with VUE hence the need for my data in gray scale.

 

I'm quite happy with my results and accuracy doesn't have to be spot on for what i'm working on at the moment.

 

It is however always good to have options if and when a project calls for a different approach in the future.

 

Attached are my current results, after applying black and white filter to my red to blue colour info, tweaking some of the channels and applying as a picture in VUE

[Peter M. Gruhn]

Channel mixer set to output gray looks to have some possibilities.

 

Painter would be good, you could set up a formula r=hue; g=hue; b=hue; Maybe throw in a little math if your hue range isn't complete.

 

One of the command line image tools like ImageMagic would probably do the job too.