Topic: Brainstorming on painting techniques

[Sarlock]

I'm back to the trees again and making some nice progress with blender.  I'm starting to produce some fairly nice looking trees now and can't wait to fully harness blender to produce different views/angles, sizes, etc, of trees with ease.

The trouble I am running in to is the massive amount of post-render processing that I have to do manually in order to get the finished render in to Simutrans.  I am producing a 32-bit alpha PNG from blender, as seen here:



But in order to remove the alpha channel I have to do a lot of manual work in choosing which pixels to keep and throw away and then saturating the background with the appropriate green hue to highlight the partial alpha sections of the tree that I am keeping.  I've tried several different approaches but they all end up being a similar amount of work.  If I can devise a faster method of converting these files then I can create the trees much faster and do a lot more experimentation/testing.

Perhaps you GIMP gurus have some ideas?  I'm still pretty new to GIMP and I am sure there are some powerful tools that I could use to assist in this conversion.

Trees are, above all others, the thing that would benefit the most from having an alpha channel in Simutrans.

[kierongreen]

You can get blender to just render with a 1 bit transparency mask.

[Fabio]

Perhaps you GIMP gurus have some ideas?  I'm still pretty new to GIMP and I am sure there are some powerful tools that I could use to assist in this conversion.

With the image(s) in a separate transparent layer:
Layer > Transparency > Threshold Alpha

It appears a dialog where you can set a threshold 0 < 127 < 255 where 127 is the default threshold and means 50% transparent / 50% opaque.

The tool transforms the Alpha channel to 1 bit (transparent / opaque) using the supplied threshold.
You can play with the threshold until you find a satisfactory level.

[Sarlock]

I knew you gurus would have some great ideas... I didn't realize I could reduce the alpha channel to a simple on/off bit.  That should make the process of conversion much easier.  I'll give it a try and see what kind of results it gives.

[Raiser]

Thank you for your replies - to make a good work i have some questions:


- Satisfiable export from Sketchup to png?

I tested different options, but I'm still not happy with the results. Many pixels get lost and the Buildings were blurred too much, equal if i do a screenshot, export with print view or use the export function of sktetchup... Who can give a useful hint? How do i sharp the Pictures effective? Which is the best method to scale the Pictures down?

- Painting antialiased lines with gimp?

how do yo do this? Which pencil adjustments do you use? Do you use layer properties?

- Easy Technique's to paint winter aspect / snowlike?

the questions are related to painting antialiased lines. Using existing tree models or winter pavement is not a problem, but painting snow?


If you provide me to create beauty computer graphics i will have many ideas for simutrans 

This for the moment...

Regards

Raiser

[prissi]

MHz used to export his images at 512 x 512 and then resized them in his paint program. This had way more options on how to handle small details.

[Raiser]

MHz used to export his images at 512 x 512 and then re sized them in his paint program. This had way more options on how to handle small details.

Do you know which 3D Software MHZ used? Its not really possible with sketchup to build and export in accurate tile size. You have to zoom out till you guess its in the correct dimension. That makes no fun I exported the church in bigger size and scaled it down with gimp so that many detail get lost...

[sdog]

I think ÆO has some experience with sketchup.

It might also a way to export to a blender compatible format and have someone render it for you with one of the working pak-pre-sets.

[mEGa]

- Painting antialiased lines with gimp?

how do yo do this? Which pencil adjustments do you use? Do you use layer properties?

No layer (becarefully with transparent action). I suggest you this link to explain how you can do :
 http://www.simutrans-france.fr.nf/doku.php?id=en:tutomakeobj2#anti-aliasing

- Easy Technique's to paint winter aspect / snowlike?

the questions are related to painting antialiased lines. Using existing tree models or winter pavement is not a problem, but painting snow?

You can proceed as us (see next Fabio's post for details) : use snow texture and apply alternatively light/dark snow color to render 3D effect

I'll post you an email with some elements as you asked by msg.

[Fabio]

These are some of my tricks:

- Easy Technique's to paint winter aspect / snowlike?

the questions are related to painting antialiased lines. Using existing tree models or winter pavement is not a problem, but painting snow?

I use (in Gimp):
- a new layer for snow
- a mask: I select all objects on the tile, then I deselect all transparecy, so that I don't risk to "dirty" it with semi-transparent pixels
- the clone tool (like a brush, but painting directly with the snow texture), with hard edge deselected; then I paint freehand giving the snow some irregular shape
- the burn/dodge (brush) tool, with hard edge deselected, giving a distinct lighting (reflections) to the jagged south edge and partly to the east one, when it seems to turn slightly towards south; I also burn parts which should be in shade
- I use snow climate official texture (i.e. that from svn) for snow on the ground, a slightly lighter one for roofs and objects

This is my specific procedure for roofs:

Inspired by mEGa, I changed my technique a little:
- I select the roof and ground area (or the whole image and then subtract the transparent parts
- I paint manually the snow using the clone tool and a soft edged brush in order to give more irregularity
- the snow is painted in a new layer for further edits
- I use for roofs a texture slightly lighter than the original one (used on the ground)
- I burn the north slope 40% darker, the west slope a 20% darker and dodge the south slope a 20% lighter
- finally I lighten or shadow manually the very edge of the roof to give the snow some volume.

- Painting antialiased lines with gimp?

how do yo do this? Which pencil adjustments do you use? Do you use layer properties?

I use often the blur (brush) tool on the edges I want to antialias.

Other times, I manage to select the edges I need (e.g. with a new layer I paint bright red lines (comic-like) on edges, possibly 2 px thick, then I use the selecy-by-color tool and hide/delete the layer and switch to the one I'm painting) and apply a gaussian blur filter, usually set to no more than 2 px.

[mEGa]

I use often the blur (brush) tool on the edges I want to antialias.

Good notice, I use too and I missed to mention it in my last comment. This share of point of views is very constructive. Thanks for this explanations.