[Gdal-dev] RE: shaded relief utility (DIY)

[Ari Jolma]

Odhiambo,

Probably you are looking for how to compute an estimate of the slope and 
aspect, from which you can compute the shading.

Usually a fit of 9-term quadratic polynomial is used. C code for 
computing that is for example here: 
http://libral.cvs.sourceforge.net/libral/libral/ral_catchment.c?revision=1.29&view=markup 
(see lines 94-260) z_factor is for cases when the unit of x and y 
differs from the unit of z.

Regards,

Ari Jolma

odhiambo george kirjoitti:
> Dear Sir,
>  
> I'm trying to write a MATLAB program for calculating or creating 
> shaded relief from a DEM. I have come across the equation attached to 
> this e-mail which i believe represents calculation of the cell values 
> heights.
>  
> What I don't undersyand is how to handle the DEM, for example, how do 
> I use the DEM together with the equation  ?
>  
> Kindly assist by shedding some light on the procedure used
>  
> Kind regards,
> George
>
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-- 
Prof. Ari Jolma
Geoinformaatio- ja paikannustekniikka
Geoinformation and positioning technology
Teknillinen Korkeakoulu / Helsinki University of Technology
POBox 1200, 02015 TKK, Finland
Email: ari.jolma at tkk.fi URL: http://www.tkk.fi/~jolma