My trees are too dark

[agillanders]

I have created a new tree image file for the random vegetation in my scenery. The problem is that it appears in the scene much darker than it should be. This can be seen clearly when comparing my trees with another tree image file.

First, here is tropical-alt.png, which is part of the standard FG distribution:


Next is my tree image file, using photos I took of some eucalypts. I have also increased the brightness of the image as part of my attempts to get the right appearance:


As you can see above, the tropical-alt.png file is much darker than my trees, but the screen shot below shows that my trees are much darker when rendered. The shot was taken at noon in clear weather. In this shot, the trees are used in two different land classes, but the land classes are identical except for tree density, so there should be no difference in the effects or shaders being used. (Or might there be? I am assuming that the only way to specify effects is in the materials file.)


(There is also too much blue in my trees as well, but that is another question.)

My question is: why might the trees in my tree image file appear so much darker than the trees in the other tree image file (which match between the tree image file and the rendered scene)? Is there something else I need to do to my tree image file to correct the way it is rendered?

Thanks in advance for any clues about this.

[Thorsten]

(There is also too much blue in my trees as well, but that is another question.)

No, in fact it's the same question.

You have a dark background underneath the fully transparent part, and the mip-mapping process mixes that into the trees. Take the transparency away in both images and you'll see the difference.

You need to carefully blend the background color (which you can unfortunately not see because it's transparent) with the tree edges such that the mip-mapping produces acceptable edges.

Since your trees have plenty of transparent pixels in the foliage, that happens pretty much everywhere and makes the whole tree dark.

[agillanders]

Thanks Thorsten. I had a quick look in Gimp for setting the colour of the background / transparency layer, but could not find it. How is that done? As for what colour to use, I would think it should be about the same as the foliage itself? Thanks.

[Thorsten]

It has to pre-exist, i.e. you first color it, then make it transparent.

[Michat]

Over GIMP menu File -->New Image, over the prompted box, > Advanced Options > filled with Transparency.
IIRC next time you restart GIMP your work space will show transparent checkered BG.

I've just opened your Eucaliptus png and I all ready get transparent BG from it. For that I guess the problem is at your workspace.

That GIMP is crazy and working with selection on trees is tedious.

Notice that BG on this forum will also create confusion, also the final results will vary a lot upon the background used.

I've made some test of your image:

1. select all > Invert selection. Lot of artifacts and ghosts founded.
2. select all> Invert selection> Export only visible as.png. Ghosts founded

I'm sorry but I think only 1 tree will match both test. Still need a lot of cleaning, but mostly amazing management of the clone tool ghost buster. Not and option to get next step to the background's test.



I encouraged you to evaluate also the main difficulty when shooting trees for FG. This is the light ( and shadows) that must be neutralized, just and only by shooting in foggy days. No other post-img can give you such neutrality of the light. Natural filter gets best chroma screen, so better selections but not success guarantied.

Thanks for sharing buddy and 29.92