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Smoothing a DEM to make it look smooth

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#1
DHissemGISCARTO

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Good day, I'm very new at this mapping but a graduate of a Cartographic Specialist program. The instructors we had seemed to not believe that DEM creation was a high priority for a Cartographer and didn't teach but 2 weeks of how to make a DEM. I have a Hillshade conversion created for a city in Ontario Canada, but trying to smooth out the roughness to make it more visually appealing like I have seen so often has me quite fustrated, I tried Illustrator, Avenza MAPublisher, and various setting in ArcGIS 9.3 but still getting the ugly coming back... Any suggestions from you Carto Gods would be appreciated and I just might name my first born after ya, depending on your screen name...

Thanks for any help

Darryl

seen attached is the mess I have so far...

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Darryl Hissem
"The virtue of maps, they show what can be done!"

#2
Charles Syrett

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Hi Darryl,

From the looks of your sample, the DEM you've selected is just too lo-res for the scale of your map. Where did you get it? Is it from the Canadian 250K series? If so, you may want to try the 50K instead. In any case, once you've made a hillshade from a DEM, you will most likely need to smooth it in Photoshop. Duplicate the image onto a new layer and then play with blurs (I like Gaussian blur myself) and/or Noise>Median. There are no procedural rules for this; it really depends on the topography on your image, as well as resolution. You just have to keep playing with it until it looks the way you want it. Don't be shy about reworking it again and again, and use the airbrush tool (on a separate layer) if needed.

Must-study resources:
http://www.shadedrelief.com/
http://www.reliefshading.com/

Don't feel bad about not getting this stuff in school. It can't really be taught in the amount of time a course would be able to alot to it.

BTW -- Where in Ontario is this? I can't quite place it.... :huh:

Charles Syrett
Map Graphics
http://www.mapgraphics.com

Good day, I'm very new at this mapping but a graduate of a Cartographic Specialist program. The instructors we had seemed to not believe that DEM creation was a high priority for a Cartographer and didn't teach but 2 weeks of how to make a DEM. I have a Hillshade conversion created for a city in Ontario Canada, but trying to smooth out the roughness to make it more visually appealing like I have seen so often has me quite fustrated, I tried Illustrator, Avenza MAPublisher, and various setting in ArcGIS 9.3 but still getting the ugly coming back... Any suggestions from you Carto Gods would be appreciated and I just might name my first born after ya, depending on your screen name...

Thanks for any help

Darryl

seen attached is the mess I have so far...



#3
DHissemGISCARTO

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Thanks Charles, I think it came from GeoBase and it might be the 250,000 scale as you said, the problem with free data I guess... I'll try again, and it's the city of Orillia I am working around, doing practice on terrain maps combined with road systems, been out of school for a bit so I need the practice. So the majority of the masterpieces I've seen so far here are helped with external software like Photoshop are they, that would explain some things, good thing I'm slightly obsessed with Photoshop and Illustrator... thanks for the suggestion Charles
Darryl Hissem
"The virtue of maps, they show what can be done!"

#4
Charles Syrett

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You can definitely get 50K DEMs from GeoBase. Interesting that you referred to Photoshop as "external" software. I tend to have a graphical approach to cartography, so I see GIS as "external". It's a way of compiling information, so that the mapmaking process can be done using graphic tools. On the other hand, I've seen some pretty amazing stuff done within Arc! B)

So....what school? Fleming?

Charles Syrett
Map Graphics
http://www.mapgraphics.com

Thanks Charles, I think it came from GeoBase and it might be the 250,000 scale as you said, the problem with free data I guess... I'll try again, and it's the city of Orillia I am working around, doing practice on terrain maps combined with road systems, been out of school for a bit so I need the practice. So the majority of the masterpieces I've seen so far here are helped with external software like Photoshop are they, that would explain some things, good thing I'm slightly obsessed with Photoshop and Illustrator... thanks for the suggestion Charles



#5
DHissemGISCARTO

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[quote name='Charles Syrett' date='Jan 12 2010, 01:05 PM' post='29195']
You can definitely get 50K DEMs from GeoBase. Interesting that you referred to Photoshop as "external" software. I tend to have a graphical approach to cartography, so I see GIS as "external". It's a way of compiling information, so that the mapmaking process can be done using graphic tools. On the other hand, I've seen some pretty amazing stuff done within Arc! B)

So....what school? Fleming?

Charles Syrett
Map Graphics
http://www.mapgraphics.com

Yes sir, Fleming College... was an interesting program, looking at going military for the Royal Military College training if I can't get work in the corporate world. Thanks for the insight, much like you I mainly use ArcGIS to compile the main files, then save them out to files that I bring into my Illustrator to do my mapping work, I like the vector aspect much more then Arc and MAPublisher doesn't hurt either...
Darryl Hissem
"The virtue of maps, they show what can be done!"

#6
RobinP

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Hi,

Did you try out the Hillshade Toolbox ? Follow the link then Model & Scripts Tab then finally, Hillshade Tool. You can smooth the Hillshade effect in the Display tab of your hillshade layer. Just Choose in the "resample during display" box the Bilinear interpolation option, it should play the trick.

Robin.

#7
kjmcgrath

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As suggested above high quality/ fine spatial resolution is the best place to start since you can always downsample... and the more pixels a smoothing filter can draws from the better the results. Personally I hillshade the DEM in arc or some other program and making sure to maintain ability to georeference the image after smoothing (via knowing location of corners of images in spatial coordinates, not changing size of image, etc.) Bring into photoshop (or like) and use median, reduce noise, gaussian blur, etc to wholesale smooth the image. If you're feeling ambitious using the burn and dodge tools on areas of shadow and illumination respectively to pull forward important features. Combination of these techniques are very effective in producing visually appealing relief. To see the work of a master look to Tom Patterson at the NPS and his excellent tutorials etc. at http://www.shadedrelief.com/

Be well




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