[Plugin] Bitmap To Mesh

MALAISE · 2 Oct 2010, 14:02

ThomThom , for your own knowledge, you should get advantages by visiting ImageJ community (OpenSource)http://www.google.fr/url?sa=t&source=web&cd=1&ved=0CBUQFjAA&url=http%3A%2F%2Frsbweb.nih.gov%2Fij%2F&rct=j&q=ImageJ&ei=ujqnTJXjIZGp4AbwxvGjDQ&usg=AFQjCNGnkzWAmC5t2IbtD4C8ayw1R0v7tg&sig2=e2-bW7zDggSXIeVI7vPRbA&cad=rja . They work around scientific pictures, and all the ways to extract informations .

Thank you really very much for all the plugins you give us.

MALAISE

Dave R · 3 Oct 2010, 11:23

Except with very small BMP files, I don't seem to have any luck. Even with a small BMP file it takes a long time to process but that could just be my computer.

Coen's comment though is intriguing. I was thinking this plugin could be a neat way to get line drawings into SketchUp. I made the attached line drawing as a quick test and got the second image as a result. I inverted the image and got the results in the third image. I wonder if it would be possible to have a control to somehow limit the range in the gray scale. Perhaps any RGB value less than, say, 250,250,250 gets read as 0,0,0? Or perhaps no height is assigned? Perhaps it isn't possible but I wonder.

Rich O Brien · 3 Oct 2010, 11:27

Making Knuckle-Dusters Dave?

Dave R · 3 Oct 2010, 11:28

Maybe I should. I was just doodling on the pad using AutoDesk Sketchbook.

thomthom · 3 Oct 2010, 11:43

@dave r said:

I wonder if it would be possible to have a control to somehow limit the range in the gray scale. Perhaps any RGB value less than, say, 250,250,250 gets read as 0,0,0? Or perhaps no height is assigned? Perhaps it isn't possible but I wonder.

It's technical possible to read values lower than 250 as 0, but I don't quite get why?
Though you can do it in PS (or similar) by adjusting the Levels.)

I have an idea of how to make the mesh less spiky though, but it needs some experimenting.

Dave R · 3 Oct 2010, 11:51

I was just thinking that setting some limit so that everything is either black or white and not shades of gray would get rid of the spikes.

Would it be possible to work things so that a face is created only if the value is less than some set point (250,250,250?) and the face is always at Z=0? Delete coplanar edges between faces and you'd have a raster to SKP converter.

Rich O Brien · 3 Oct 2010, 12:02

I like that idea

Kind of Footprint or Ink Stamp tool, lots of uses for it too!

thomthom · 3 Oct 2010, 12:24

@dave r said:

I was just thinking that setting some limit so that everything is either black or white and not shades of gray would get rid of the spikes.

The spikes you see if much due to the extreme height of the mesh, and part due to the current triangulation. I'm not sure if making the contrast bigger will reduce then - in either case, Ruby isn't efficient for image manipulation - you'd be just as well off just preparing the image before in an proper image editor.

@dave r said:

Would it be possible to work things so that a face is created only if the value is less than some set point (250,250,250?) and the face is always at Z=0? Delete coplanar edges between faces and you'd have a raster to SKP converter.

It'd be an interesting new tool, but I still think it's best if the image is prepared by the user in an editor and made into complete Black and White (not grey scale).

Then the tool could read all the white or black and generate a mesh - where it could then afterwards trace the outline and remove the interior lines. After running an curve simplification, like the Douglas-Peucker algorithm , and you could end up with a decent vectorized shape from your raster mask.

This would have been so much better if I could read the alpha channel of PNG files. I was a looking at this some time ago, but existing too many third party libraries for my comfort which makes redistribution more complex. The alternative, making a pure standalone ruby PNG interpreter wasn't so easy either, the decompression algorithm wasn't the easiest.

Dave R · 3 Oct 2010, 12:31

Well, it's all voodoo to me so I am glad we have folks like you.

thomthom · 3 Oct 2010, 14:56

Version 0.2.0b

Made into a tool so the user can easily position the mesh
Moved menu to Draw > Mesh From Bitmap
Keeps aspect ratio of image or Image element
Right click and Image element to generate a mesh. (Does not need to be BMP image - but Draw > Mesh From Bitmap still require BMP imput)
Colour BMP images will convert the RGB value to optical greyscale.
VCB support

thomthom · 3 Oct 2010, 15:57

Test using sample maps from: http://www.mtgrafix.com/programs/terrain.html

Also tried this: http://www.twisteddirt.com/TutorialStuff/dem_02.php Nice terrain shape - but the diffuse texture wasn't so good.

dedmin · 3 Oct 2010, 15:58

thomthom · 3 Oct 2010, 16:07

308px × 1 047px - that would make the mesh ~500-600K faces?

And the issue with that bitmap is that despite it being a greyscale, it's still not a height map - which is why the mesh doesn't come out looking as what the image illustrate.

dedmin · 3 Oct 2010, 16:11

Yes, true. I just wanted to test it - the file is 105 MB

thomthom · 3 Oct 2010, 16:18

Yea - the last texture I tested was 512x512 - heavy mesh. And I'd forgotten that Autosave was on - every 5 mins. x_X

dedmin · 3 Oct 2010, 16:20

dedmin · 3 Oct 2010, 16:30

shura · 3 Oct 2010, 21:30

Why don't I get the Curve Simplification to work?

thomthom · 3 Oct 2010, 21:41

hm... possibly you have a version where it failed on closed loops. I might not have uploaded a corrected version...