Pictures of grass.  They'll be my downfall...

A while back I posted an image of a stupid robot happily running around a
grass knoll.  That picture took, like, FOREVER to render.  And I mean almost
two days (if memory serves me right).

Then I discovered mesh2.  Yow!

I modelled some blades of grass in hamaPatch (see the pic), exported to
Wavefront OBJ format (sub-division 3, kids), converted them to
mesh2 with 3DWin and then set them lose over a heightfield using trace().

The resulting image uses 125,000 copies of the grass mesh2 object (and 1000
mesh2 flower objects for a bit of colour) and took about 10 minutes to
render (AA0.3, 800x340, GUI and Render priority normal).

The only problem with this pic is the flowers.  (They're not meant for close
scrutiny!)  Fog in 3.5 beta 10 (windows) does not seem to like targa
image_maps with alpha channels.  If I take out of the fog, the problem
disappears.  I don't think its a max_trace_level problem or similar - any
ideas?  Genuine bug?

Bye,
Alan.

Post a reply to this message

Attachments:
Download 'hamaPatch grab.jpg' (36 KB) Download '35grass-v4_07.jpg' (67 KB) Download 'withfogwithout.jpg' (43 KB)

Preview of image 'hamaPatch grab.jpg'

Preview of image '35grass-v4_07.jpg'

Preview of image 'withfogwithout.jpg'

Did you try to use hollow on for the flowers?

Post a reply to this message

"JRG" <jrg### [at] hotmailcom> wrote in message
news:3c5efcca@news.povray.org...
> Did you try to use hollow on for the flowers?
>

I have now...!

Partly solved the problem, but there's still a ghosting effect (see pic).

Post a reply to this message

Attachments:
Download 'withfog2.jpg' (19 KB)

Preview of image 'withfog2.jpg'

Which fnishes are you using? You may want to use a texture map to avoid highlighting
etc. on the transparent parts.

--
Jonathan.

"Alan Holding" <tro### [at] tiscalicouk> ha scritto nel messaggio
news:3c5efefe@news.povray.org...
> "JRG" <jrg### [at] hotmailcom> wrote in message
> news:3c5efcca@news.povray.org...
> > Did you try to use hollow on for the flowers?
> >
>
> I have now...!
>
> Partly solved the problem, but there's still a ghosting effect (see pic).
>
>
>

Post a reply to this message

This looks great. I would like to try it. Approximately how many triangles
in each blade of grass? Do you think that removing the normals might speed
up the render even more without detracting from the appearance? If I wanted
to do this in PoV, would it be faster to subdivide a mesh until I get a
desired smoothness, or to let PoV form a beizer patch? Is there a method for
accessing the triangles which make up a patch and converting them via macro
into a mesh?

Sorry about the number of questions.

-Shay

Alan Holding <tro### [at] tiscalicouk> wrote in message
news:3c5ee125@news.povray.org...
>
>

Post a reply to this message

"Shay" <sah### [at] simcopartscom> wrote in message
news:3c5f02e1$1@news.povray.org...
> This looks great. I would like to try it. Approximately how many triangles
> in each blade of grass? Do you think that removing the normals might speed
> up the render even more without detracting from the appearance? If I
wanted
> to do this in PoV, would it be faster to subdivide a mesh until I get a
> desired smoothness, or to let PoV form a beizer patch? Is there a method
for
> accessing the triangles which make up a patch and converting them via
macro
> into a mesh?
>
> Sorry about the number of questions.
>

Er...

Number of triangles?  Well, there's 434 vertex_vectors, 1386 normal_vectors,
686 face_indices - so that makes, er - dunno, really!  :O)

Will removing the normals detracting from the appearance?  I suspect it
would.  I've made mesh objects 'by hand' before (little macros to create
mesh heightfields from trace()d isosurfaces) and if you mess up the normals
the object tends to look terrible.

Further subdivision?  I dunno.  Do you want the hamaPatch object and my
script so you can try for yourself?

I've used patch objects before (straight export from hamaPatch) but the
speed difference between them and the mesh2 version makes it no contest for
me - mesh2 wins hands down.

As for the last one - isn't this a waste of time?  If you want to convert a
hamaPatch object into a mesh for usage in POV, why not let 3DWin do the hard
work?  If you want to convert a 'hand made' patch into a mesh, I think you
can use a combination of Warp's Mesh Compressor and Chris Colefax's
associated include files (been a while since I used them so I'm not sure).
Go here to find out more: http://www.geocities.com/ccolefax/

I'm no POV expert, so can anyone else chip in to help Shay?  My head's
beginning to hurt!

Alan.

Post a reply to this message

"Alan Holding" <tro### [at] tiscalicouk> wrote in message
news:3c5f217b@news.povray.org...
> As for the last one - isn't this a waste of time?  If you want to convert
a
> hamaPatch object into a mesh for usage in POV, why not let 3DWin do the
hard
> work

I am NO artist. A large amount of the pleasure I get from using PoV is
figuring out how to do things. If you look at my POVs got juice! post, you
will see what you might consider a HUGE waste of time (building mesh objects
by hand.)

Thank you very much for the help. I think I will probably build a blade out
of just a few triangles and subdivide the most curved parts then add normal
vectors and write the mesh to an .inc file. OR the lazy way, build each
blade out of about 10K vertices and write a macro to remove the unnecessary
ones.

 -Shay

Post a reply to this message

Alan Holding wrote:


> The only problem with this pic is the flowers.  (They're not meant for close
> scrutiny!)  Fog in 3.5 beta 10 (windows) does not seem to like targa
> image_maps with alpha channels.  If I take out of the fog, the problem
> disappears.  I don't think its a max_trace_level problem or similar - any
> ideas?  Genuine bug?


I don't know what causes it, but I've seen v3.0 do the same. In my case 
it was an indexed-color targa, with one color set as transmit 1. Did you 
use indexed color or alpha channel? Did you try image_pattern?

John Haiducek

Post a reply to this message

"John Haiducek" <jha### [at] umichedu> wrote in message
news:3C6### [at] umichedu...

> I don't know what causes it, but I've seen v3.0 do the same. In my case
> it was an indexed-color targa, with one color set as transmit 1. Did you
> use indexed color or alpha channel? Did you try image_pattern?

Used a TGA image map with an alpha channel.  The code for the texture is:

#declare txt_uv_orange_flower=texture {
  pigment {image_map {tga "uv_orange_flower.tga" once interpolate 2}}
 finish {ambient 0.1 diffuse 1 phong 0}
 normal {bump_map {tga "uv_orange_flower.tga" once interpolate 2
bump_size -10}}
}

Just tried changing the image type to PNG with an alpha channel (saved from
Paint Shop Pro v7.04 if you're interested), but still no better.

Ho hum.

Post a reply to this message