GIMP Script: Thatch

[RobA]

As I have been tormenting gimp users in this thread with promises of this script being complete, I think it is ready for prime time

; Version 2.5 (20080209)

Description:
This will "thatch" a heightfield with a specified pattern. with the pattern rotated to line up "downhill"
If there is a selection, only the area within the selection will get thatched.

Location:
Filters->Atristic->Thatch...

Parameters:
"Invert the heightfield" - unchecked expects high=1, checked will use high=black
"Select a thatch pattern" - the pattern to cover the surface with. It should really be a tileable pattern
"Pattern 'downhill' orientation" - "Right" "Up" "Left" "Down" reflects the downhill sloping direction of the pattern
"0 angle offset (degrees)" - adjust the lighting base angle, from 3:00, 0 to 360 degrees, ccw.
"Number of 'faces' to calculate" - The number of downhill directions to create
"Blending between 'faces'" - The number of pixels to blur and overlap each of the faces. This doesn't blur the waterline.
"Flat area strength" - Adjust how close to flat a section of the heightfield has to be to get the omni directional blend of the pattern. Set to 0 will use NO omni directional blend layer.
"Make 0 elevation transparent" - checking this turns the 0 elevation transparent in the final result. unchecked it will be considered as a flat area and get the omni directional blend
"Create a bumpmap layer" - check this to add a bumpmap layer in overlay mode on top.
"Lighting angle for bumpmap" - if the above is checked, the angle for the lighting.
"Create a softlight layer" - if checked, a "white high" copy of the heightfield will be added, at 50% opacity in softlight mode
"Merge thatching to one layer" - if checked, the resultant thatch image is merged down to one layer, otherwise all of the layers are left to allow manual adjustment. It doesn't merge the bumpmap or softlight layers, however.
"Create new image" - if checked, the thatch will be a new image, otherwise it will be new layers in the existing image.

The script requires as input a greyscale heightfield image. It uses a FLATTENED version of the current image, so any non-heightfield layers need to be hidden.

The other thread has examples galore, starting on page 2. here are some screen grabs in use...

The heightfield with the area selected to thatch:
t_docs1.jpg

The Thatch script dialog:
t_docs2.jpg

The result (you can see the script reduces the area as small as it can):
t_docs3.jpg

And the layer stack created for these options:
t_docs4.jpg

Oh yeah. I am using a scaled down version of Redrobes' thatch as a pattern. (it is also rotated 90 degrees because the earlier versions of the script required it to be that way...)

The rest of the demo textures I used came from a variety of texture sites that I took and scaled down... Here is a Google Search.

-Rob A>

[RobA]

OK -

I discovered what could become another use for this script... making mountain heightfields.

From above (gimp alone):
mtn_final.png

Rendered in 3D:
hf1.png


I started with a selection filled with a shaped spherical fill:
mtn_hf1.png

Then using this pattern I made:
pattern1.png

I ran the thatch script with 7 sides, no bumpmap or softlight, merging all layers down. I set the result to multiply, 30%:
mtn_hf2.png

cont...

[RobA]

Then using this pattern:
pattern2.png

I ran thatch again, setting the result to 30% multiply as well:
mtn_hf3.png

And a third time with this pattern:
pattern3.png

With one last run of thatch, with the result to 30% multiply:
mtn_hf4.png

I think by tweaking the patterns, possibly making them more turbulent or noisier, I could even get closer.

-Rob A>

[Hoel]

This could be a reason to finally start migrating from PS to GIMP. Looks awsome!

[Karro]

Oh, hm. I'm going to have to look into this one and experiment. This could solve a problem I was contemplating: something that was going to take me a lot of work to brute-force... Hmm.

[jfrazierjr]

I am not a fan of the top down one due to the repeating texture, though it has a nice potential for a good starting place, BUT, the POVRay 3D one is super frackinlicious!!! Could you try to do a few slightly overlapping heightfields (with various overlap amounts and see what a mountain range might look like (especally the 3D version)??

Perhaps I could use this as a base and then use the smudge tool to muddy it up a bit to get rid of the repeating pattern and apply a bump map on a 50% grey layer set to overlay might work really well to have some nice foldy creases and crevasses.

[Steel General]

Cool stuff as always RobA - you just may get me to go over to the GIMP-side one of these days.

[Karro]

I am not a fan of the top down one due to the repeating texture, though it has a nice potential for a good starting place, BUT, the POVRay 3D one is super frackinlicious!!! Could you try to do a few slightly overlapping heightfields (with various overlap amounts and see what a mountain range might look like (especally the 3D version)??

Perhaps I could use this as a base and then use the smudge tool to muddy it up a bit to get rid of the repeating pattern and apply a bump map on a 50% grey layer set to overlay might work really well to have some nice foldy creases and crevasses.

Hmm. Doing some kind of a selection on the grey-scale, then using the smudge-tool, with a bit of jitter, and stroke the selection, maybe that would be a quick way to get rid of the repeating pattern. Would that even work?

[torstan]

So I have a slightly unrelated question - what program are you using to convert the heightfield to a 3D render?

[töff]

This could be a reason to finally start migrating from PS to GIMP. Looks awsome!

Being a happily mind-numbed Adobephile, may I ask which part of this GIMP procedure doesn't translate somehow to Photoshop?