4.3 | 3 ratings Rate this file 26 downloads (last 30 days) File Size: 3.42 KB File ID: #14863

Hillshade

by Felix Hebeler

03 May 2007 (Updated 07 May 2007)

No BSD License

calculates a hillshade for a DEM (matrix)

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Description

Function to calculate hillshade for a digital elevation model. Derives slope and aspect in radias to calculate shading value between 0 and 255 using a given lighting angle and altitude.

Altitude (angle above ground) and angle (direction/aspect) of lightsource can be given via args.

Derived using ESRIs hillshade algorithm, but uses simple GRADIENT function instead of Horns algorithm for slope calculation - factor 30 more efficient & no need for IP TB. (Thanks to Andrew Stevens)

Pls leave you feedback/rate.

MATLAB release

MATLAB 7.3 (R2006b)

Tags for This File
Everyone's Tags	aspect, dem, hillshade, shading, slope
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Comments and Ratings (4)
03 May 2007	Andrew Stevens	Well done! Easy to use, good comments and produced a nice result for me. Thanks. One question: could something like the "gradient" function be used instead of nlfilt. That way, users wouldn't need the IP toolbox to implement.
05 May 2007	Felix Hebeler	Implemented the GRADIENT function - thanks for the suggestions and code, its much faster now...
13 Mar 2008	Giuliano Langella	I find very useful this function. I wonder if you have implemented also other hydrological/geomorphological functions in MatLab, such as PLAN/PROFILE curvatures, etc. I suggest the following call to hillshade function in case of R reference matrix: >> h = hillshade(Z, (R(3,1)+R(2,1)):R(2,1):(R(3,1)+size(Z,2)R(2,1)), R(3,2)+R(1,2):R(1,2):(R(3,2)+size(Z,2)R(1,2))); with R = [0,-cellsize; cellsize,0; up_left_pixel_X,up_left_pixel_Y]; Thanks.
22 Aug 2008	Evana Rosylee	hi, i was refering to your code on finding the slope and aspect up til the gradient part.it really is good and it helps me alot.now,i have a DEM image of 1400x1400 in bitmap format,grayscale(0-255).I need to pick two points on the pixel in order for me to calculate the slope and aspect.my problem now is,how can i automatically run for every pixel in the image?i know i have to use the loop function but i don't know how.any suggestion is welcome..thank u~

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Updates
04 May 2007	Update to set hillshade 0 for values <0. Include example.
07 May 2007	Changed calculation to use GRADIENT function instead of nlfilter. Increases calculation speed by factor 30 and does not need ImageProcessing TB.
07 May 2007	fixed small bug in the options parsing, clearified help.

Tag Activity for this File
Tag	Applied By	Date/Time
hillshade	Felix Hebeler	22 Oct 2008 09:11:28
dem	Felix Hebeler	22 Oct 2008 09:11:28
shading	Felix Hebeler	22 Oct 2008 09:11:28
aspect	Felix Hebeler	22 Oct 2008 09:11:28
slope	Felix Hebeler	22 Oct 2008 09:11:28