Hi(gh)!

On 30.06.2013 00:30, Cousin Ricky wrote:
> =?ISO-8859-1?Q?J=F6rg_=27Yadgar=27_Bleimann?=<yaz### [at] gmxde>  wrote:
>> The main problem seems to be that
>>
>> trace(Earth_Slice, Earth_Pos,
>> 2*rd*<sin(radians(-Cam_Long))*cos(radians(Cam_Lat)),
>> sin(radians(Cam_Lat)), cos(radians(-Cam_Long))*cos(radians(Cam_Lat))>)
>>
>> which probes for the mesh, always returns zero... why?
>
> Try adding a 4th parameter:
>
>    #declare Norm =<0, 0, 0>; //dummy assignment
>    trace(Earth_Slice, Earth_Pos,
>    2*rd*<sin(radians(-Cam_Long))*cos(radians(Cam_Lat)),
>    sin(radians(Cam_Lat)), cos(radians(-Cam_Long))*cos(radians(Cam_Lat))>,
>    Norm)
>
> If Norm is<0, 0, 0>  after the call to trace(), then the trace has missed the
> object entirely.

After setting the background to white for better visibility, I found out 
that I forget to put the two parts of the scaling factor for the vertex 
vectors in brackets - so the mesh2 ended up in a completely different 
location than defined by the geographical coordinates!

Originally, it was:

         rd+hval*<vertVect>

with rd being Earth's radius and hval the terrain elevation value gained 
from the pixel colour of the heightfield.

Of course it must be:

         (rd+hval)*<vertVect> !

Attached below is what I've got... still at a low test resolution, but 
the three main islands, Tristan da Cunha, Inaccessible and Nightingale, 
are clearly discernible!

Now let's go for a full-resolution view...

See you in Khyberspace!

Yadgar

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