| Re: shaded relief [message #52163] |
Fri, 19 January 2007 03:48  |
greg michael
Messages: 163
Registered: January 2006
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Senior Member |
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Thanks Paulo - that's a good suggestion. It works. Unfortunately it
brings a new problem: now the image is very low contrast (because of
the reduced range of slopes), having a brightness range of only about
10/256. After stretching it doesn't look very good. Now I think of it,
I'm surprised the object-graphics one doesn't look the same. There must
be some auto-stretching going on there. Maybe this is a killer for the
direct-graphics way?
Greg
IDL> z=dtm*128./58000.+50.
IDL>
shade_surf,z,image=sh,az=0,ax=90,position=[0,0,762,768],tick =0,xstyle=1,ystyle=1,xrange=[0,768],yrange=[0,768],zrange=[0 ,768]
Paolo Grigis wrote:
> Have you tried fiddling around with {x,y,z}range keywords in
> shade_surf to get the right aspect ratios for the axis?
>
> Ciao,
> Paolo
>
> greg michael wrote:
>> I want a method to generate fast shaded relief views from a surface
>> elevation grid (pixel for pixel orthogonal views which overlay)
>>
>> I tried using direct graphics with something like:
>>
>> shade_surf,dtm,image=sh,az=0,ax=90,position=[0,0,768,768],ti ck=0,xstyle=1,ystyle=1
>>
>> This works, except that the z-scale is auto-scaled producing an
>> unrealistic exaggeration. shade_surf doesn't take an /isotropic
>> keyword.
>> [...]
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