Hi,

I have a specific scene in mind. I want to create a smooth land with small
hills. From the camera, surface goes down and comes back up in the
distance.  I was'nt able to create a heightfield that can be rendered as I
wanted. Heightfield generators seem to work well for randomly created
terrains but not for specific topologies. I tried terragen and was very
unhappy with the result.

1) Is there a an easy way to paint the heightfield in any tool?

2) Isosurface seems promising but need some guidence. Isosurface tutorial
was not helpful for generating a special terrain.

Thanks in advance

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Architect nous apporta ses lumieres en ce 2005-07-20 13:58:
> Hi,
> 
> I have a specific scene in mind. I want to create a smooth land with small
> hills. From the camera, surface goes down and comes back up in the
> distance.  I was'nt able to create a heightfield that can be rendered as I
> wanted. Heightfield generators seem to work well for randomly created
> terrains but not for specific topologies. I tried terragen and was very
> unhappy with the result.
> 
> 1) Is there a an easy way to paint the heightfield in any tool?
> 
> 2) Isosurface seems promising but need some guidence. Isosurface tutorial
> was not helpful for generating a special terrain.
> 
> Thanks in advance
> 
> 
All in POV Ray:
You can light a plane with lights, some with negative colour. Place a spot_light where
you want the 
ground to rise. Place a negative one for low parts that are still to high. You can
then add some 
pigment to get some variations.
In your case, there should be a light near the wanted camera position, another for the
hill in the 
distance, maybe a cylindrical parallel negative one grazing the plane for the dip.
Render as TGA and use glabal_settings{hf_grey_16). place the camera to look
perpendicular to the 
plane, generaly, it's good to use an orthorgaphic camera for that kind of renders.
You now have an hight_field you can use in your scene. You need to scale it to the
actual size of 
your scene (start as contained in a 1*1*1 box set one corner at the origin)

Using the windows version, enter "+ft" in the text box left to the resolutions list.
You can also 
set the size of the image using +w<width> +h<hight> (-w100 -h76 for example to get a
100*76 image).

For a sample of this trick, you can look at the crater_dat.pov sample in the objects
folder. It use 
3 spot_light to create a crater hight_field.

Alain

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>
> 1) Is there a an easy way to paint the heightfield in any tool?

Any paint program should allow you to produce an image that you can base the 
height field on.

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"Josh" <s### [at] acom> wrote:
> >
> > 1) Is there a an easy way to paint the heightfield in any tool?
>
> Any paint program should allow you to produce an image that you can base the
> height field on.

Just create a grey-scale image (the bigger the better, so as to get some
good resolution), with tonal values that range between black (lowest
elevation) to white (highest elevation), then save it in one of the file
formats POV supports for heightfields. Note that most image editors create
8-bit images, not 16-bit.  This means that no matter how LARGE your image
map, the grey-scale values will still be "divided up" into a set number of
finite steps. That is, changing the size or resolution of the image won't
alter this min. to max. tonal value. So even with a large-size (or
high-resolution) image, you'll still probably see some "stepping" in the
vertical direction of the generated heightfield, particularly when you
scale up the HF in that direction. 16-bit images have MUCH finer grey-scale
"steps." But in my experience, even Photoshop doesn't create or edit 16-bit
images. POV -Ray itself does, strangely enough!  (See the comments made
earlier.)

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Architect wrote:
> Hi,
> 
> I have a specific scene in mind. I want to create a smooth land with small
> hills. From the camera, surface goes down and comes back up in the
> distance.  I was'nt able to create a heightfield that can be rendered as I
> wanted. Heightfield generators seem to work well for randomly created
> terrains but not for specific topologies. I tried terragen and was very
> unhappy with the result.

Try planetgenesis...  http://planetgenesis.sourceforge.net/

It has a number of different noise generators and you can combine them 
in different ways. Some ripples with a gradient should get what you 
describe.

> 1) Is there a an easy way to paint the heightfield in any tool?
> 

Check out Cinepaint http://cinepaint.sourceforge.net/

It can handle 16 bit greyscales, I use it to tweak the output from 
planetgenesis, great for carving rivers and stuff...

RG

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"Kenneth" <kdw### [at] earthlinknet> wrote:
> Note that most image editors create
> 8-bit images, not 16-bit.  This means that no matter how LARGE your image
> map, the grey-scale values will still be "divided up" into a set number of
> finite steps. That is, changing the size or resolution of the image won't
> alter this min. to max. tonal value. So even with a large-size (or
> high-resolution) image, you'll still probably see some "stepping" in the
> vertical direction of the generated heightfield, particularly when you
> scale up the HF in that direction. 16-bit images have MUCH finer grey-scale
> "steps." But in my experience, even Photoshop doesn't create or edit 16-bit
> images. POV -Ray itself does, strangely enough!  (See the comments made
> earlier.)

I'm pretty sure the whole NetPBM package can work with 16-bit .ppm images,
although some programs may not function correctly with high bit depths. See
http://netpbm.sourceforge.net/README

NetPBM is the 'home' of the .ppm family of image formats. These command-line
programs are quite stable, having been around for ages. They are very handy
for processing huge images & batch processing.

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