what are they what do they do?


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http://www.geocities.com/siliconvalley/horizon/7128
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                                                                    Joe

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Joe Conklin wrote:

> what are they what do they do?
>
> --
> http://www.geocities.com/siliconvalley/horizon/7128
> visit and sign the book
> remove "spam" to reply
>
> Joe

I will give a simple explanation because it is the only one I know.

1. You use a height field to make mountains (other stuff too, suppose).
2. A heightfield is actually a normal 2D picture (looks like one of
those arty tie-died Tshirts).
2b. Pov looks at each color in the tie-die, works out its number  (each
color is numberred), and that is the height of the mountain at that
point.
3. there are a couple of utilities you can use to generate them, and you
can even use win paintbrush, but you would have to be skilled or stupid.

4.  To use, a) generate the heightfield somehow (I use terrain maker)
                 b) do the 'insert>shapes>heightfield' thing in POV3.0
                 c) under filename, put the one you want to use

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Jarrod Hart wrote:

> Joe Conklin wrote:
>
> > what are they what do they do?
> >
> > --
> > http://www.geocities.com/siliconvalley/horizon/7128
> > visit and sign the book
> > remove "spam" to reply
> >
> > Joe
>
> I will give a simple explanation because it is the only one I know.
>
> 1. You use a height field to make mountains (other stuff too, suppose).
> 2. A heightfield is actually a normal 2D picture (looks like one of
> those arty tie-died Tshirts).
> 2b. Pov looks at each color in the tie-die, works out its number  (each
> color is numberred), and that is the height of the mountain at that
> point.
> 3. there are a couple of utilities you can use to generate them, and you
> can even use win paintbrush, but you would have to be skilled or stupid.
>
> 4.  To use, a) generate the heightfield somehow (I use terrain maker)
>                  b) do the 'insert>shapes>heightfield' thing in POV3.0
>                  c) under filename, put the one you want to use

  Jarrod,

   I am having a similar problem.  I am working on a project to use POV-Ray
in Radio Astronomy.  My problem is that I have a "contour map" in false
color that I want to use as my height field.  That way, I can get a good
estimate of the shape of the radio source.  Do you know of anyway to do
this?  I am basically wanting to turn a 2d map into a 3d contour map.

Any help would be appreciated from anyone,

Bob Ratliff
Morehead State University
Morehead Astrophysical Observatory

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> 
>   Jarrod,
> 
>    I am having a similar problem.  I am working on a project to use POV-Ray
> in Radio Astronomy.  My problem is that I have a "contour map" in false
> color that I want to use as my height field.  That way, I can get a good
> estimate of the shape of the radio source.  Do you know of anyway to do
> this?  I am basically wanting to turn a 2d map into a 3d contour map.
> 
> Any help would be appreciated from anyone,
> 
> Bob Ratliff
> Morehead State University
> Morehead Astrophysical Observatory

Just a little tip: If your image is in 256 colours you may want to
re-order the pallete so that the lowest colour is at top and the highest
colour is at the botto, or is that the other way round??? Anyway, povray
uses the pallete and the order of the colours in it to determine which
colour is the highest point in the image and which colour is the lowest.
The read the docs. Try 7.5.2.5(it contains all the gory details about
heightfields.)

Cheers, Matthew

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Using a global setting of "hf_gray_16" aids in creating a smooth and
precise field. The larger you render the first step the better the final
image will appear (to a point).
  This may not create an image as you expect it to appear, but it will
nevertheless have three dimensional characteristics. I came up with the
following two files to create hf's from any image. Even a black&white image
can benefit from this process (and has).

On the first pass, use this file to create your height_field input file.
----------------------------------------------------------------------------
-----------
// FC_HF.pov

global_settings { max_trace_level 25 assumed_gamma 2.2 hf_gray_16 }

object { box { <-4,-3,1>,<4,3,1.1> } texture {
   pigment { image_map { tga "FalseColor.tga" once }
   translate <-.5,-.5,-.5> scale <8,6,1> } } }

camera { location <0,0,-5> direction z look_at 0 }
light_source { <0,0,-65500> color rgb 1 }
----------------------------------------------------------------------------
-----------
Then, use this file to finish it up.
----------------------------------------------------------------------------
-----------
// Final.pov
height_field { tga "FC_HF.tga" smooth rotate -90*x
texture { pigment { image_map { tga "FalseColor.tga map_type 0 once } } }
translate <-.5,-.5,-.5> scale <8,1,6> translate 1*z }

camera { location <0,0,-5> direction z look_at 0 }
light_source { <0,0,-65500> color rgb 1 }
----------------------------------------------------------------------------
-----------
Additionally, you can rotate the height_field in the final source in order
to see the 3D effects.
--
Paul Hinds
gri### [at] swbellnet

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GrimDude wrote:

>  Using a global setting of "hf_gray_16" aids in creating a smooth and
> precise field. The larger you render the first step the better the
> final
> image will appear (to a point).
>   This may not create an image as you expect it to appear, but it will
>
> nevertheless have three dimensional characteristics. I came up with
> the
> following two files to create hf's from any image. Even a black&white
> image
> can benefit from this process (and has).
>
> On the first pass, use this file to create your height_field input
> file.
> -----
> ----------------------------------------------------------------------
>
> -----------
> // FC_HF.pov
>
> global_settings { max_trace_level 25 assumed_gamma 2.2 hf_gray_16 }
>
> object { box { <-4,-3,1>,<4,3,1.1> } texture {
>    pigment { image_map { tga "FalseColor.tga" once }
>    translate <-.5,-.5,-.5> scale <8,6,1> } } }
>
> camera { location <0,0,-5> direction z look_at 0 }
> light_source { <0,0,-65500> color rgb 1 }
> -----------------------------------------
> ----------------------------------
> -----------
> Then, use this file to finish it up.
> ------------------------------------
> ---------------------------------------
> -----------
> // Final.pov
> height_field { tga "FC_HF.tga" smooth rotate -90*x
> texture { pigment { image_map { tga "FalseColor.tga map_type 0 once }
> } }
> translate <-.5,-.5,-.5> scale <8,1,6> translate 1*z }
>
> camera { location <0,0,-5> direction z look_at 0 }
> light_source { <0,0,-65500> color rgb 1 }
> -----------------------------------------
> ----------------------------------
> -----------
> Additionally, you can rotate the height_field in the final source in
> order
> to see the 3D effects.
> --
> Paul Hinds
> gri### [at] swbellnet

Good files, Grimdude, but, especially for a case where you are trying to
accurately render a dataset, I recommend that you create the height
field with an orthographic camera and ambient 1.0 to avoid false
perspective and shading artifacts.  This also makes it easy to make the
height field exactly fit the false color image.  Also, if you set
assumed_gamma to 1.0 and set display_gamma to 2.2 (or 1.8 or whatever)
in your .ini file, your colors will have better dynamic range, there
will be less need for pumping color values over 1 (and losing some
detail), and people with nonClone machines will be able to run your
POV's and get the same results as you.  I posted a .zip a day or two ago
that illustrates these things if you are interested.  Aside from these
quibbles, it uses the same basic two step approach you describe.

Jerry Anning
cle### [at] dholcom

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Oh, you mean the 345Kb thing? Heh, I was afraid to look :)

--
Paul Hinds
gri### [at] swbellnet

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Bob Ratliff wrote:

>    I am having a similar problem.  I am working on a project to use
> POV-Ray
> in Radio Astronomy.  My problem is that I have a "contour map" in
> false
> color that I want to use as my height field.  That way, I can get a
> good
> estimate of the shape of the radio source.  Do you know of anyway to
> do
> this?  I am basically wanting to turn a 2d map into a 3d contour map.

The first thing is that, if possible, the *brightness* of your false
color should correspond to the parameter that you want to map.  Given
that, the higher the resolution (the larger the size), the smoother your
image will be.  What you do, basically, is first, use the false color
image to make a special format gray scale height field map.  Then, you
use that to render the height field and lay the original false color
image on it.  The accompanying .zip file contains an example of the
process.  Gradmap.tga was randomly splotted together in CorelPaint.
Call that our original false color contour map.  It was fed to
gradhgt.pov, which was rendered with gradhgt.ini.  This produced
gradhgt.tga, a 16 bit grayscale height field map.  Using gradhgt.tga to
form the height field and gradmap.tga to color it, the final image,
gradimg.tga. was produced with gradimg.pov and gradimg.ini.  I used
POVWin to do this, but any version of POV would work.  Email if you need
a hand or more info.  This is easiest if your original map is square, as
this was, but other aspect ratios can be accommodated.  Good luck.

Jerry Anning
cle### [at] dholcom

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Attachments:
Download 'htfields.zip' (345 KB)

Jerry, et al..

   Thanks for the information and the files.  I will see if what I can do
using them and let you know how it goes.  I am also trying to do the
same thing using Hi-Q which my boss thinks might do it easier, but if
it is easier, I have yet to find a way ;)

Thanks,

Bob Ratliff
Systems Administrator
Morehead Astrophysical Observatory
Morehead State University

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Joe Conklin <spa### [at] csrlinknet> wrote in article
<34d5373f.0@news.povray.org>...
| what are they what do they do?
| 
| 
| --
| http://www.geocities.com/siliconvalley/horizon/7128
| visit and sign the book
| remove "spam" to reply
|                                                                     Joe
| 
| 
|

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