Reverse Quantizing, AKA - how to get a heightfield from contour lines

[Redrobes]

In terms of stitching arbitrary height maps may I point you at some work done by Howard Zhou who has been working on this sort of thing for a while...

http://terrain.cg-arts.org/forum/ind....msg821#msg821
http://www.howardzzh.com/research/terrain/

To keep it simple, I believe he is finding the closest path between two maps and cutting along them - a bit like photo stitching I think. I reckon there is a lot more to it tho. Its unbelievably awesome actually. Anyways there is a world machine plug in to do it.

[HandsomeRob]

http://www.howardzzh.com/research/terrain/

That looks amazing. Being a professional cartographer I have a very large supply of real-world DEMs to use as source files, and it looks like this is just the application to create the mountain ranges, valleys, canyons, etc. for my world. But I could not find the download.

I WANT.

[Redrobes]

The public interface to this utility is a plugin for WorldMachine.

http://www.terrainsynthesis.org/worl...rger/index.htm

[su_liam]

Okay, here's my experiment.

First, I took the quantized image and applied a 2.5-pixel Gaussian Blur to start. Next, I applied the Spatter filter at a radius of 8 and a smoothing of 1.

Next, I tried a smaller 1.3-pixel blur, and a spatter at the same settings as before. I repeated this a couple times.

I finally did a blur at 2.8 pixels to reduce the spots a bit.

This is what I was thinking of calling my Stochastic Deterrace Algorithm. I'm not sure how satisfactory this is. What do you think?

[su_liam]

Next, I tried a morphological close operation: an erode followed by a dilate. I was hoping to denoise it a bit. Basically, I copied the image, pasted it as a channel. Used the channel as a selection then expanded the selection by one pixel, followed by a 1-pixel contraction of the selection. Then I saved the selection as a channel, copied the new channel and pasted it into a new layer. Didn't really help.

Finally, I tried Filter>Noise>Median... with a radius of 7 pixels. Here is the result.

See what you think?

[su_liam]

I rendered the last heightfield in Bryce. There's a lot of moiré, edges are significantly rounded and there's still a very noticeable terracing.

I'm going to try applying just a touch of smoothing in bryce, but the SDA even with a last Median stage is feeling pretty busted. I had such high hopes, too...

[RobA]

The banding was even noticeable in the greyscale version of the last one. Good try though!

-Rob A>