I thought I would share this info.

Playing around with the GeoControl height_field program, I experimented with 
the "seamless" feature which I had not yet really used. The possibilities 
are interesting. In POV-Ray, I built this test, either by rotating or by 
flipping the base height_field generated by GeoControl. The result is a 
landscape wich shows little repetitions that are too obvious for the eyes. 
They are there of course, but more distributed over the whole surface. The 
seams however, are really invisible, and that is excellent.

Thomas

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Attachments:
Download 'HF_seamless_test.jpg' (58 KB)

Preview of image 'HF_seamless_test.jpg'

To go a step further, it is interesting to see how GeoControl achieves this 
(see images from the help). The four edges are symmetrical but flipped.

As a side discussion to the "Heightfield to isosurfaces?" thread started by 

there a possibility to achieve something similar using POV-Ray?

Thomas

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Sorry. Forgot the images.

T

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Attachments:
Download 'seamless2.jpg' (10 KB) Download 'seamless1.jpg' (10 KB)

Preview of image 'seamless2.jpg'

Preview of image 'seamless1.jpg'

Thomas de Groot wrote:

> is there a possibility to achieve something similar using POV-Ray?

What exactly is it you wish to achieve within POV-Ray?

As far as I can see, if you use an external heightfield,
its either seamless or not, and if you have some kind of
function for the terrain you don't really need tiles as
you already get arbitrary extent and resolution?

But it's an interesting construct, I never thought of
projective planes in terms of landscape tiling - I was
actually thrown off track for a bit by the unusual array
directions but I'd still say its a projective plane ;)

http://en.wikipedia.org/wiki/Fundamental_polygon

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"Thomas de Groot" <tDOTdegroot@interDOTnlANOTHERDOTnet> wrote:
> I thought I would share this info.
>
> Playing around with the GeoControl height_field program, I experimented with
> the "seamless" feature which I had not yet really used. The possibilities
> are interesting. In POV-Ray, I built this test, either by rotating or by
> flipping the base height_field generated by GeoControl. The result is a
> landscape wich shows little repetitions that are too obvious for the eyes.
> They are there of course, but more distributed over the whole surface. The
> seams however, are really invisible, and that is excellent.
>
> Thomas

I tried to accomplish something similar when I created the Hill objects in my
Sprites Collection:

http://lib.povray.org/searchcollection/index2.php?objectName=GameSprites&version=2.0&contributorTag=SharkD

However, my thinking was not so organized, and my ad-hock attempts were not
successful.

-Mike

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"Christian Froeschlin" <chr### [at] chrfrde> schreef in bericht 
news:4942ef4b$1@news.povray.org...
>
> What exactly is it you wish to achieve within POV-Ray?
>
> As far as I can see, if you use an external heightfield,
> its either seamless or not, and if you have some kind of
> function for the terrain you don't really need tiles as
> you already get arbitrary extent and resolution?
>
> But it's an interesting construct, I never thought of
> projective planes in terms of landscape tiling - I was
> actually thrown off track for a bit by the unusual array
> directions but I'd still say its a projective plane ;)
>
> http://en.wikipedia.org/wiki/Fundamental_polygon


You are perfectly right on all points. In fact, I didn't think this through 
obviously as indeed, in POV-Ray, you can use a function and not use tiles at 
all. So consider my question as gone down the drain.

Thanks for that page on projective planes. My math knowledge is not up to 
understanding this, but I have an idea now how GeoControl uses this.

Thomas

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