Hi Chunk,
The fuzziness you see is under sampling due to the texture being
captured in objects space rather than in screen space - one texel on
the overlay texture is being sampled by many screen pixels. Ideally
you want a 1:1 mapping, but this is very hard to achieve and different
algorithms are supported by OverlayNode to help address it. See the
enum:
enum OverlayTechnique
{
OBJECT_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY,
VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY,
VIEW_DEPENDENT_WITH_PERSPECTIVE_OVERLAY
};
VIEW_DEPENDENT_WITH_PERSPECTIVE_OVERLAY is the one with most
sophisticated support trying to better map overlay texture with the
requirements of view.
Robert.
On Feb 19, 2008 3:04 PM, Cole, Charles E. (LARC-B702)[GENEX SYSTEMS]
<[EMAIL PROTECTED]> wrote:
> Hi,
>
> I'm trying to create a grid overlay on a TerraPage database. I searched
> the archives and examples and found the osgsimulation, osgspheresegment,
> and osgscribe examples to be very helpful. I've implemented a grid
> overlay (and the code is very similar to osgspheresegment). However,
> I'm getting some "fuzziness" to the grid lines.
>
> I've attached two screen captures. The first is the grid that I'd like
> to overlay. The second is the grid overlaid on the terrain using the
> osgSim::OverlayNode. What's happening is the grid lines are getting
> "fuzzy" when applied as a texture. What I'd like is the crispness of
> the grid as shown in the first picture to be overlaid on the terrain.
> Does anyone know some quick hints or explanation of why this is and what
> I can do to get a more crisp line on the terrain?
>
> I'm a definite newbie when it comes to textures. So, there may be
> something very simple here, but I've tried to do some searching on this
> behavior and I just can't find anything.
>
> Any help or guidance with this would be greatly appreciated.
>
> chuck
>
>
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>
>
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