On 28-8-2017 9:27, Stephen wrote:
> On 28/08/2017 07:56, Thomas de Groot wrote:
>> On 27-8-2017 19:23, Sven Littkowski wrote:
>>> Hi,
>>>
>>> as many know, i want to work on a number of Martian renders. I
>>> downloaded from the NASA 3D Resources website a number of Martian 3D
>>> surface files, but sadly, they all are in a very low resolution, lots of
>>> triangles and corners.
>>>
>>> At the same time, I am seeing on the Internet some renders that show
>>> some very impressively detailed martian landscapes, among them my Valles
>>> Marineris. But these renders were done long time ago, around 2004.
>>>
>>> Does anyone here know, where to get POV-Ray usable hi-res Mars 3D
>>> surface files? I do not have the ability to convert Hi-Rise images.
>>>
>>
>> I suppose these lower res meshes are posted by NASA in order to reduce 
>> the 'weight' of the files.
>>
> 
> I think it is the other way round. The High Res meshes are made 
> available as a courtesy. You can't expect NASA to give it a high 
> priority when no one in their right mind would try to build a planet in 
> High Res. What would the memory requirements be anyway?

I am lost now. The Nasa meshes we downloaded from NASA (like Valles 
Marineris) are they considered hi- or lo-res? Additionally, I think that 
mesh landscapes always show a resolution problem; so do height_fields 
too of course, and both when used for a close, detailed, view. I don't 
think there really is a solution for that, except using the 
mesh/heightfield for background or mid-range view, and a separate, 
local, one for a detailed foreground. That is what I do in those cases.

> 
> 
>> What you can do with your own meshes is to subdivide them in Poseray. 
>> However, you may be in trouble rapidly as the file becomes too large 
>> for OpenGL to redraw the mesh, I found out. I don't know if the 
>> subdivided mesh can still be saved (I didn't try). Somebody with a 
>> better suggestion?
>>
>>
> 
> No more than two subdivisions, I would say. Can PoseRay displace faces 
> along their normal? (I don't have it installed atm.)
> 

You can do displacement mapping, if that is what you mean, but that is 
tricky. I don't know how good MeshLab is for these kind of 
manipulations, by the way. Might be worth the try.

-- 
Thomas

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