First try on a two-pass 3d engrave. Took almost two hours for the 3.75" square. Proofgrade Thick Draftboard.
I cleaned it up with some orange pumice soap and a stiff brush. Couldn’t seem to get the char out of the deepest parts of the engrave.
Source file was a heightmap of the DC area I pulled from USGS
Probably would look better if it was printed larger, but that would take quite a while!
Whoa. Is that PG draftboard?
Yes (updated original post.)
Again! Unbelievable! 
That’s very Neat! I expected the USGS would have some good source material…
They do, although their website, in typical government fashion, is late-90s web 1.0, so it’s a bit of a PITA to work with.
The geography rendered as a grayscale depth map makes it looks like a closeup image of the interior of an eyeball.
The resulting print doesn’t though. Looks pretty neat.
The color one looks like the crust of the pie I had last night.
The B&W version looks like something @henryhbk just pulled off of the x-ray server.
Seriously that’s pretty awesome. 3.75" eh? Got some very cool detail out of the draftboard!
I’m curious… I’ve never done 2 passes on anything. And I’m still unclear under what circumstances one would choose to do a 2nd pass. So, what made you do it? I mean, especially since this is a 
setting on material, why wouldn’t the settings just… be right?
I think it’s a matter of trying to “extract” more depth out of the engrave. I’m sure it engraved fine on the first pass, but doing a second will make deeper parts deeper, if you will.
Btw, if you do a fast uniform pass on that (basically just a big single-color square) you can probably get rid of the color difference.
I don’t understand what this means. Fast engrave over the already 2-pass engraved part? That’d get rid of the charring, you mean?
@csader is right. Subsequent passes pronounces detail of depth.
So @dan, does this mean that auto-focus is fully operational?
fancier than “extract more depth” 
Yep. All you need to do is zap a thin surface layer. (When I was experimenting with 3D engrave on wood before it went PG, I would typically do two passes for depth and then one more very light and fast for char.)
Oh, I’ve been on it and you are SO correct. But luckily part of my brain still remembers late-90s web 1.0 (I was a “Web Master” back then!) so it isn’t too foreign. 
Paul… That’s fascinating. Burning more reduces the char?! I’m guessing by some noticeable amount?
When you say light and fast, can you give me some idea of what you’ve used there?
If you want an updated web experience, the Aster DEM data is also available on NASA’s Earthdata site:
I was just thinking that it looks like a rustic home-made cracker.
Well… the setting was right there!
Perhaps I should have titled this “Deep 3D Engrave” rather than 2-pass, but it’s the same thing. It’s only an option on Thick Proofgrade and I wanted to see what the behavior was. My expectation is that if I did a regular 3D engrave on both thin and thick Draftboard, they would look pretty much the same (be engraved to the same depth) whereas the Deep engrave would essentially exaggerate the terrain by 2x.
I think what he’s saying is to do a very low-power pass over the whole thing after it’s done, which should be enough to vaporize the char but leave the wood intact without causing more char. I saw this technique mentioned in another thread some time ago, and I’ll give it a try next time. If it works well I’ll suggest that the Proofgrade setting include a “Finishing Pass” checkbox!
I don’t think this has anything to do with autofocus… it’s creating the varying depth of engrave by continuously varying the laser power as it scans across.
