Why is Blender doing this?

[Pamela Galli]

v 2.63

I am trying to bake a column with adjacent railings.

One one side it looks like this -- see how the railing does not match up with the bake? I closed and reopened the file, same thing.

 

 

[WADE1 Jya]

I think what's happening there is you're fighting with the resolution of your UV map. Pixels are a set size so when precision is needed, these sort of rounding errors can be a struggle. What I do in these situations is just hand edit the bake artistically to make it fit.

The quicker alternative in SL is just up the resolution of your map and this probably goes away. Best practice is working at the smallest resolution before 'things look crappy' but with SL likely never landing on mobile platforms probably doesn't matter.

[Pamela Galli]

I don't understand how the resolution affects it.  On the other side of the column the bake looks like this:

[Ciaran Laval]

Might be rotations of your faces in the UV Map. Can you rotate the face 180 degrees on the UV map?

[WADE1 Jya]

The reasoning behind that is just math. Think placing random size objects into neat rows of little boxes all the same size. Some of the objects just won't fit evenly. There's going to be bits poking out. That's how lightmapping is calculated, it scatters fake 'photons' across the object and approximates on a per-pixel basis.

The fact it was only wrong on one side was what made me think of this. In these case, upping resolution gives you closer fit (you can probably lower it again later, PS handles this well), or you can just tweak things around a bit manually.

Could be other things of course.

It could just be you shifted something accidentally like what happens to me after cat lays on my keyboard. Try rebaking.

[Drongle McMahon]

I think you may have somehow got the wrong part of the baked texture on the wrong face of the column - since the dark bit is too high on one and too low on the other. Difficult to suggest exactly how without knowing what the UV mapping is. Perhaps either the image or the map got flipped?

[Pandorah Ashdene]

I had similar problems in various situtations (the ambient occlusion or texture of a meshpart 'meeting' a surface not being in the 'spot', where the mesh actualy met the surface); this is what I figured out about the problem and the 'solution' always worked for me:

I assume you are modeling (like most people do, including me) in rectangular faces (quads) and not in triangles; the quad can be split two ways into two triangles; if you do not do that yourself, the dae converter will do it before you make the upload to SL; so, 'in' SL the mesh will have triangular faces only; Blender does this quad to triangle splitting as well 'on the fly' while you are looking at the mesh (in textured view), and it does the split when rendering the ambient occlusion or any other bake.

The problem I observed with Blender is that it makes a difference which way the quad is split, and what basicaly happens is that Blender splits the quad for the AO calculation in one way, despite using the opposite split for display;

I solved all this mess by simply splitting the quad in question myself (quad to trig) and forced Blender thus to use the same quad split for the bake process and the display (and finaly as well for the dae export);

[Pamela Galli]

Thanks to everyone who took the time to share insights!  Yes I rebaked many times, deleted the column and copied another one and baked it, same thing. Blender thinks the railing is higher than it is and that's that.

I finally decided to do the easiest thing and just move the railing up to where Blender thought it was.  It is not level with the other perpendicular railing but that is probably not noticeable.

[Ashasekayi Ra]

Not sure if this helps. But, the other night, I had the worst problem with this figure ending up in every bake of this one outfit. It drove me nuts. Later, I realized that I had a backup copy of the figure hidden on the same layer as the outfit. Once I moved it to a new layer, the bake came out as expected.

 

[Masami Kuramoto]

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Pamela Galli wrote:

Thanks to everyone who took the time to share insights!  Yes I rebaked many times, deleted the column and copied another one and baked it, same thing. Blender thinks the railing is higher than it is and that's that.

I finally decided to do the easiest thing and just move the railing up to where Blender thought it was.  It is not level with the other perpendicular railing but that is probably not noticeable.

---

I agree with Drongle. Unless this is a bug in Blender 2.63 (Why don't you install the latest version?), there must be something wrong with your UV layout. Due to aliasing it is normal for bakes to be up to one pixel off, but in your picture it's clearly more than that. As usual, since all we have is screenshots, there is no way for anyone of us to tell exactly what's going on. However, I can prove that Blender's bake function is as accurate as it gets.

The worst you should ever see is something like this:

The best way to avoid these effects is to design the model as constructive solid geometry, i.e. instead of making separate meshes intersect one another, use boolean modifiers to merge them into a single mesh. Then your ambient occlusion bake will look like this:

[Pamela Galli]

Yes this is not just artifacts.  Blender just thinks the railing is where it is not. But I moved the railing where Blender wants it so now all is good.

OT but: As far as making one mesh rather than several, it depends on LI (and to some extent how much I want to have components I can reuse).  Sometimes having things in one mesh means a big LI hit, sometimes it reduces it.  Depends on the bounding box created.

 

 

[Masami Kuramoto]

Can you isolate the problem or reproduce it with a smaller model, e.g. two cubes? Or at least have Nacy take a look at it. These things are not supposed to happen, and changing the model to match the bake is hardly an acceptable solution.

[Pamela Galli]

I sort of reproduced it. The railing is between two columns, so after I moved the railing up and baked the other column, Blender remembered where the column had been before I moved it up.  So I can have the railing match one column or the other but not both.

I think I already overwork Nacy, though she is always ready to cheerfully help.  (I feel like some child learning to crochet, getting things all knotted up, having to give it to some adult to fix.)

 

It is not a big deal, I can fix it in Gimp, just wondered if anyone here knew what the deal was. 

[Masami Kuramoto]

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Pamela Galli wrote:

I sort of reproduced it. The railing is between two columns, so after I moved the railing up and baked the other column, Blender remembered where the column had been before I moved it up.  So I can have the railing match one column or the other but not both.

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I think you created the second column by duplicating the first but forgot to make single-user copies of the assigned image. Both columns now share one image, and every time you bake either of the columns, the bake result of the other gets overwritten.

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It is not a big deal, I can fix it in Gimp, just wondered if anyone here knew what the deal was. 

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Only noobs fix broken bakes in Gimp or Photoshop. Come on, Pamela, you can do better than that.

[Pamela Galli]

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Masami Kuramoto wrote:

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Pamela Galli wrote:

I sort of reproduced it. The railing is between two columns, so after I moved the railing up and baked the other column, Blender remembered where the column had been before I moved it up.  So I can have the railing match one column or the other but not both.

---

I think you created the second column by duplicating the first but forgot to make single-user copies of the assigned image. Both columns now share one image, and every time you bake either of the columns, the bake result of the other gets overwritten.

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It is not a big deal, I can fix it in Gimp, just wondered if anyone here knew what the deal was. 

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Only noobs fix broken bakes in Gimp or Photoshop. Come on, Pamela, you can do better than that.

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No the bake is not the same on the columns.  One column has two railings intersecting, one just one. Anyway I restarted Blender and it baked fine on both.  Blender does sometimes get stuck on something and nothing fixes except sometimes a restart.

I am a mesh noob. I just happen to work like I always have -- somehow get things made without really having the skills to do it. Here is my first mesh house, an English Cottage and garden, which I wrested into being by sheer force of will -- Nacy helped me when I got stuck (like with LODs which I could not get uploaded), and made the lighting, and we made the door handles together, but most of it I did myself (took me 3 months):

 

 

 

 

 

 

[Masami Kuramoto]

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Pamela Galli wrote:

Anyway I restarted Blender and it baked fine on both

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Wait a minute... Are you saying that this was your first Blender restart since the beginning of the thread? You moved the railing around, fixed the textures in Gimp etc., but you didn't restart Blender until now? You've got to be kidding.

Don't get me wrong; if this is in fact a bug in Blender, I'm all for reporting it and getting it fixed, which is why I'm here, wasting my time trying to figure out what's going on. However, there are some things odd about this one:

• You keep reporting the same issue again and again, see here.
• You never provide a .blend file, only screenshots.
• No one ever manages to confirm the bug.
• After about three days, you say: Never mind, it's fine now.

[Pamela Galli]

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Masami Kuramoto wrote:

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Pamela Galli wrote:

Anyway I restarted Blender and it baked fine on both

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Wait a minute... Are you saying that this was your first Blender restart since the beginning of the thread? You moved the railing around, fixed the textures in Gimp etc., but you didn't restart Blender until now? You've got to be kidding.

Don't get me wrong; if this is in fact a bug in Blender, I'm all for reporting it and getting it fixed, which is why I'm here, wasting my time trying to figure out what's going on. However, there are some things odd about this one:

• You keep reporting the same issue again and again, see
  here
  .
• You never provide a .blend file, only screenshots.
• No one ever manages to confirm the bug.
• After about three days, you say: Never mind, it's fine now.

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That is not the same issue -- that is issue was caused because I had some box checked that I should not have, which someone in the thread identified.  About a week ago Drongle confirmed a problem I was having as a bug with that version.

The great majority of the time when I ask for help here, someone does come up with an answer or solution -- this forum is a very valuable resource.  You, however, are certainly under no obligation to "waste your time" reading -- in fact, please do consider yourself specifically excluded from my intended audience.

[Masami Kuramoto]

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Pamela Galli wrote:

That is not the same issue -- that is issue was caused because I had some box checked that I should not have, which someone in the thread identified.

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After the checkbox was identified as a possible cause, you insisted that it was not checked when you started the bake, and you claimed that only a program restart magically fixed the problem.

Now you are doing the same thing again. You are asking us to believe that after three days of searching and trying, a simple restart suddenly fixed everything. You gladly accepted all the helpful clues but now refuse to share the actual solution, just like last time. Probably because that information could be valuable to other people struggling with Blender, who may end up becoming competitors. Eat the free lunch and keep blaming the cook, that is your motto.

[Ashasekayi Ra]

Wow Masami.

What exactly are you trying to accuse Pamela of? Making up bugs to make Blender look bad or having actual bugs that she doesn't share the fix to? It really can't be both.

As for her sharing .blend files, why would she since she is obviously working on merchandise for her business.

When someone posts a problem on this forum, none of us are obligated to respond or "waste their time" as you put it. I'd also point out that there are a number of threads on this forum where people new to Blender post a question and come back later and say "nevermind, I figured it out". She is hardly the only one.

[Ciaran Laval]

That's a very nice build Pamela, I haven't got to making curves yet at all.

[Pamela Galli]

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Ciaran Laval wrote:

That's a very nice build Pamela, I haven't got to making curves yet at all.

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Well this is a good example of how I make things despite not having all the skills I need. At this point in time, I could make the arch for the windows in Blender, but when I started the house I did not know how, so I made it in Sketchup and imported it.

[Pamela Galli]

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Masami Kuramoto wrote:

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Pamela Galli wrote:

That is not the same issue -- that is issue was caused because I had some box checked that I should not have, which someone in the thread identified.

---

After the checkbox was identified as a possible cause, you insisted that it was not checked when you started the bake, and you claimed that only a program restart magically fixed the problem.

Now you are doing the same thing again. You are asking us to believe that after three days of searching and trying, a simple restart suddenly fixed everything. You gladly accepted all the helpful clues but now refuse to share the actual solution, just like last time. Probably because that information could be valuable to other people struggling with Blender, who may end up becoming competitors. Eat the free lunch and keep blaming the cook, that is your motto.

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I had opened and closed the file several times to no effect; when I restarted Blender, yes, the problem was fixed, however wildly far-fetched that may sound to you.  How that constitutes "not sharing the solution" I do not know.

Let me explain how I have learned almost everything I know: by not being the least bit afraid to reveal my ignorance in forums.  You are not the first person to express disbelief that anyone could be as dumb as I am and make all the stuff I do.

How about you go right now and put me on Ignore, as I will you?  Problem solved!

[Masami Kuramoto]

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Ashasekayi Ra wrote:

Wow Masami.

What exactly are you trying to accuse Pamela of? Making up bugs to make Blender look bad or having actual bugs that she doesn't share the fix to? It really can't be both.

As for her sharing .blend files, why would she since she is obviously working on merchandise for her business.

When someone posts a problem on this forum, none of us are obligated to respond or "waste their time" as you put it. I'd also point out that there are a number of threads on this forum where people new to Blender post a question and come back later and say "nevermind, I figured it out". She is hardly the only one.

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It's a matter of courtesy, Asha.

If your call for help in a community forum results in multiple responses suggesting possible solutions or workarounds, you don't just walk away after you got what you were looking for. You contribute back by sharing the solution that worked for you -- especially if it is one that you figured out by yourself --, so that the thread is useful to other people running into the same problem later.

Pamela doesn't do that. The last time she had a problem with ambient occlusion bakes, she didn't even give a nod to the person who pointed her in the right direction. Instead she claimed that the problem magically went away after a program restart. Today we know that this wasn't true.

And here we have it again. The miraculous program restart that fixed everything -- after three days!

I didn't expect her to share the entire .blend file she was working on. I asked her to isolate the problem in a smaller model which contained nothing but those few elements that were causing the trouble, so that someone else could take a look at it and eventually attach it to a bug report at blender.org. Apparently I was already asking too much.

You are right, sometimes people post a question and immediately follow it up with "Never mind, I figured it out" if the answer is obvious. But very few people do so after several days of guessing and a dozen suggestions. Because that is just impolite. And it is also short-sighted because people may feel less inclined to help in the future once they realize that favours don't get returned.

[Jacki Silverfall]

Can't anyone with the same problem read the same thread and get the same answers as Pamela? I don't see why she needs to come back and say "hey it worked" when the information is right there in the thread. 

Hardly anyone comes back to give gold stars. And we shouldn't expect it.

[Pamela Galli]

I really have a hard time understanding Masami. The thread he referenced was pretty much the opposite of everything he said.  In this thread, I have thanked the ppl who made suggestions -- something I rarely forget to do -- answered questions, and reported the solution to the problem. Evidently Masami thinks I am lying to foil any competitors who might have the same problem -- how weird is that? 

Also if someone in this thread asked for the blender file, I did not see it. And he goes on about "THREE days".  Well, recently Nacy spent three days pulling her hair out before discovering it was indeed a Blender bug. Another problem file she discovered was due to accidentally checking the wrong box. And nacy is not a noob.

Here is an inexhaustive list of what might be the problem when working with Blender (and most software):

1. User error -- maybe any one of the bazillion settings is wrong.

2. Corrupted file.

3. Reproducible Blender bug

4. Glitch fixed by reopening the file.

5. Glitch fixed by restarting Blender.

Three days is just not an unreasonable time to sort out what the problem is and come up with a fix.