Jump to content

 
Photo

Improving Hillshade in ArcMap

- - - - - hillshade arcmap landserf aspect bias toolbox script

  • Please log in to reply
2 replies to this topic

#1
HK120

HK120

    Newbie

  • Validated Member
  • Pip
  • 7 posts
  • Gender:Male
  • Location:Switzerland
  • Switzerland

The following hillshading was created with the hillshade tool (spatial analyst) in ArcMap 10. Its DEM is from SRTM (1 arc-sec, about 26m resolution). It covers 18km on the ground. No image improvements done.

 

Attached File  srtm1_arcmap.png   480.98KB   77 downloads

 

When I calculate hillshade from the same underlying DEM in Landserf (http://www.landserf.org) with applied vertical exaggeration = 1 and aspect bias 50 (from 0 to 100), and with the same light direction, then it looks like the following: This one is better, less rugged and the features appear clearer. Also the aspect bias of 50 gives stronger contrasts. 

Attached File  srtm_landserf.png   396.56KB   69 downloads

 

How can I implement such a hillshading method from Landserf in ArcMap so that it yields a similar result? Exist somewhere useful Toolbox-scripts? (For example I have found the Swiss Hillshade model from from ESRI Mapping Center).  And especially, how can I implement an aspect bias function? 

 

I'm very thankful for any hints and suggestions.

 

 

 



#2
Matthew Hampton

Matthew Hampton

    Hall of Fame

  • Moderator
  • PipPipPipPipPipPipPip
  • 1,282 posts
  • Gender:Male
  • Location:Portland, Oregon
  • Interests:Playing in the mountains and rivers.
  • United States

Hi HK120,

 

Welcome to the forum!  

 

I don't have any experience hillshading with Landserf and I'm not 100% sure what the 'aspect bias' function does, but I am thinking you could achieve better results in ArcGIS by creating a multiple-direction-oblique-weighted (MDOW) hill shade.  This integrates a couple different light sources to help illuminate the terrain more effectively.  For example you could use the traditional NW illumination at 85% and SE illumination at 15% - experiment to get your desired outcomes relative to the terrain and resolution of the data.

 

I find both surfaces you created to be slightly noisy (bumpy), and would suggest you run a circular focal mean in ArcGIS to smooth things out a bit.  Again experiment to get your desired results (3x3, 5x5, 10x10).


Oregon Metro - Portland, OR
www.oregonmetro.gov


#3
benjamin543

benjamin543

    Newbie

  • New Member
  • Pip
  • 2 posts
  • No Country Selected

Hi,

Both abowe mentioned suggestions are valid and a part of standard toolbox. However, there are many better alternatives out there. For bumpines definitely use the mdenoise filter (use through GRASS, SAGA or standalone app, all freeware).
As far as hillshade itself MDOW produces too much gray in the flats. 2 more advanced approaches one can apply in ArcGIS + freeware are combining hillshade with 50% of SkyViewFactor a.k.a. SWF (SAGA or standalone freeware apps) or curvature.
I do realize that the instruction are a bit sketchy but with a bit of googling it shouldn't be difficult.

Cheers

Ben





Also tagged with one or more of these keywords: hillshade, arcmap, landserf, aspect bias, toolbox, script

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

-->