Using Wings3D to Fix Topology

The Prob­lem

Most full-blown 3D appli­ca­tions come with “sub­di­vi­son sur­face edit­ing” facil­i­ties of some sort. The tools used for this, how­ever, are basi­cally just polyg­o­nal mod­el­ing ones, applied to the con­trol cage rather than the sub­di­vi­son sur­face itself. As they often got devel­oped before sub­di­vi­sion sur­faces even got added as a fea­ture to such appli­ca­tions, they are more or less ter­ri­ble at guar­an­tee­ing that the sur­face one’s edit­ing is actu­ally stay­ing man­i­fold.

How­ever, non-manifold geom­e­try fre­quently pro­vides to be the opener for a can of worms at ren­der time. Just recently, a col­league at work asked me for help to fix a model done in Maya. While look­ing fine in Maya’s view­port, it would ren­der as a sub­di­vi­son sur­face with com­pletely screwed up tex­ture coor­di­nates in Pho­to­Re­al­is­tic RenderMan.

The rea­son being that it con­tained non-manifold geom­e­try. The ren­derer detected this and threw the offend­ing parts of the mesh away, print­ing a warn­ing mes­sage. Due to a bug though, it didn’t adjust the rela­tion­ship with the tex­ture coor­di­nate data accord­ingly. Which led to the bad image.

Now there’s two solu­tions: report a bug to the ven­dor of the ren­derer or make sure your geom­e­try is ‘good’ (man­i­fold) for starters.

With dead­lines loom­ing, the lat­ter is com­monly the only option. What we tried first in the case at hand was hence to run Maya’s Poly­gon Cleanup tool on the mesh to ensure man­i­fold­ness. Maya’s tool not always detects cer­tain sorts of non-manifold con­nec­tiv­ity though. As was the case with the mesh at hand. So we couldn’t fix the prob­lem in Maya.

I’ve come across this issue numer­ous times in recent years. Hav­ing ‘good’ meshes come out of the mod­el­ing depart­ment can save you so much trou­ble later down the pipeline, its impor­tance can’t be stressed enough.

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A Comment on the iPhone 4’s “Retina Display” Debate

Sev­eral blogs and mail­ing lists I fre­quent linked to an arti­cle inves­ti­gat­ing the valid­ity of Apple’s claims that the iPhone 4′s dis­play has a ‘ter­mi­nal’ res­o­lu­tion for the appli­ca­tion at hand: namely a human read­ing its dis­play at an ‘aver­age’ dis­tance (which, being unspec­i­fied in Apple’s press release, offers quite a bit of lat­i­tude for interpretation).

The arti­cle ignores sev­eral impor­tant facts.

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On Plagiarism & Creativity in the Digital Age

A while ago there was a thread on the 3D-Pro mail­ing list that diverged from its orig­i­nal sub­ject and took a turn towards a debate about copyright.

The debate resulted when some­one dis­cov­ered that part of an image was being used as a back­drop for another image with­out giv­ing proper credit. It is note­wor­thy that the lat­ter work was not of com­mer­cial nature. The poster got very upset about this nev­er­the­less. I think what upset them most was the fact that the cre­ator of the derived work claimed copy­right. The poster called that per­son an “artist” (they used quotes to express their dis­agree­ment with the use of that term) who had “the filthy guts to rip of another (real) artist’s hard work”.

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Planet Japan

I arrived in Tokyo last week but due to the sen­sory over­load this city imposes on the brain, par­tic­u­larly on a geek’s brain, I needed some time to con­tem­plate (read: process) my impres­sions before writ­ing any­thing about it.

Let me start by say­ing that I feel utterly stu­pid, by now, for not hav­ing vis­ited Japan ear­lier. My aunt is Japan­ese; through her I got to watch “Naus­caä of the Val­ley of the Wind” (in Japan­ese, w/o sub­ti­tles), when I was 11 years old, in 1985, the year after the movie came out. The images never left my head and I believe they were part of the rea­son I ended up pur­su­ing a career in film.

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