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Author Topic: Object editor - face colour  (Read 3277 times)

AlecJames

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Object editor - face colour
« on: August 21, 2013, 10:23:14 am »

Hi all

I've made an object by combining meshes / linking up points / filling in faces, etc. pic attached.
(I want to "print" a 3D object via an stl file)

In my attached picture one face is shown much darker than the others.  This is not intentional and I cannot find what I have done to it to make it appear this way.  If I apply a material to the whole object this face shows a darker shade of the applied material.  What could I have done to cause this?

Thanks
A
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kreator

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Re: Object editor - face colour
« Reply #1 on: August 21, 2013, 11:37:13 am »

Are the faces transposed? Or are you using a bump map within the material?


I find using a bump map in 0.97D causes the model to go black although it renders out ok.
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O

$imon

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Re: Object editor - face colour
« Reply #2 on: August 21, 2013, 11:45:11 am »

It's hard to see from this angle, it could be some geometry that's messed up, or an inverted normal..

maybe if you post the model we can try to fix it.
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AlecJames

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Re: Object editor - face colour
« Reply #3 on: August 21, 2013, 12:38:24 pm »

I don't understand "faces transposed", what does it mean?

I had problems with the exported stl until I flipped normals on all faces that didn't select yellow on the outside surface.

I've attached the model, I'm curious about what I've done...

No intentional bump map. I set the material to 'default'.  I've used mainly 097d but the file has also been changed in 097e.

The stl looks OK but it it will be tomorrow before I get a 3d print.

Thanks
A
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ENSONIQ5

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Re: Object editor - face colour
« Reply #4 on: August 21, 2013, 01:09:51 pm »

There's nothing wrong with the face, it's just Anim8or's object-mode screen shading.  If you rotate the whole object 90 degrees around the vertical axis you'll see the face appears to change colour.
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AlecJames

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Re: Object editor - face colour
« Reply #5 on: August 21, 2013, 02:44:21 pm »

It does not change shade for me?  Also, if I drop it in a scene and spin the camera around it , that face also shows up much darker.  The oposite 45 degree face has 2 different colours for different parts of the surface - different faces of that surface are different colours...
(I know one face has rendered incorrectly (breaks into the hole) which I can fix by breaking the face into smaller sections.)

In object mode: If I put a simple cube next to the block and spin the two together, I can see the shading changing on the cube faces. This looks different to that dark grey face on my block.

Thanks
A
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cooldude234

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Re: Object editor - face colour
« Reply #6 on: August 21, 2013, 05:36:10 pm »

Im pretty sure it's the normal screwing up. Anim8or sometimes miss-calculates the face normals when building solids. What you could do is try selecting the face and going into edit and clicking on flip normals.

To to tell if a normal is flipped, when you select a face from behind it shows up blue, if its facing you it turns yellow.
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AlecJames

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Re: Object editor - face colour
« Reply #7 on: August 21, 2013, 05:44:59 pm »

Hi cooldude234, I had problems with the exported stl until I flipped normals on all faces that didn't select yellow on the outside surface.  I tried anyway and it made no difference. I also tried deleting the faces and putting them back without luck.   What is "Fix Normals"?  (although its greyed out for me)
Thanks
A
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dwsel

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Re: Object editor - face colour
« Reply #8 on: August 22, 2013, 12:03:14 am »

Have you tried exporting to *.obj and reimporting? Some Options->Debug like 'Log file import' or 'Check structure' might be useful (although it's just a guess as I haven't tested these options in the work)
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Raxx

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Re: Object editor - face colour
« Reply #9 on: August 22, 2013, 03:02:47 am »

AlecJames, I'm assuming you made the object in a separate program and imported it into Anim8or, or used a script to do the boolean operations. If not, my apologies, but either way you need to pay more attention to the mesh structure. Also, as ENSONIQ5 stated, there was nothing really wrong with the face in question, aside from the problems mentioned below.

Your model has several problems. You had edges floating out by themselves for no reason, had another couple of edges connecting points where they shouldn't have, the tesselation needed improving on several faces since it caused concave polygons, you had duplicate points, and in general stuff just needed fixing.

I'm attaching a .an8 file that contains both the "fixed" version and the original. Be sure to compare the two objects to see the changes I made. It "should" export and slice fine now, but I may have missed something.
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ronaldefarmer

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Re: Object editor - face colour
« Reply #10 on: August 22, 2013, 04:06:36 am »

Hi AlecJames,

I wonder if perhaps the faces in question don't change shade as expected because you're because you are using the arc-rotate to turn it. This seems to move the "camera" rather than the object. What happens if you use the rotate tool on the side toolbar instead?

Ron
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AlecJames

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Re: Object editor - face colour
« Reply #11 on: August 22, 2013, 09:56:06 am »

Hi Raxx, I made the object entirely in Anim8or.  Yesterday I an edge going nowhere and deleted it.  Is there an "easy way" to find unconnected edges or do you do it by inspection?
I only added the tesselation to make fill holes work.  Fill holes and I don't get along; a hole with several points at the top of my 45 degree cyclinder will not fill or it fills and and the face appears to break over into the bore of the cylinder.  I can fix this by adding egdes to each hole so it only has three edges.
Duplicate points I try to fix using merge points, it there an easy way to know when you have 2 points overlapped?
(I really struggle to "see" the correct points that need to be linked together- takes me hours.  I put it down to lack of skill :)   )

How can you tell when a face has concave polygons?

Hi Ron,   You've spotted what I'm doing - I'm using the arc rotate tool instead of rotating as Ensoniq5 suggested.

Thanks all. BTW I've printed the part and its come out OK.
A
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Raxx

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Re: Object editor - face colour
« Reply #12 on: August 23, 2013, 09:00:40 am »

Basic cleanup operations you can use:
  • Edit->Select->Select Malphormed Edges - Selects edges that have more than two faces attached to them
  • Edit->Select->Select Orphans - Selects points and edges that do not compose a face.
  • Edit->Merge Points - Simple method to cleanup duplicate points
  • Edit->Fix Normals (enabled if you have the mesh selected) - Makes sure all faces adjacent to each other are facing the same direction
  • ASL Scripts, such as the complex cleanup script by Kubajzz

Generally, smart modeling and awareness are the best tools to keep a model "clean". You acquire this with experience, and by paying attention to the consequences of every operation you perform. Personally, I don't even use those cleanup operations, not just because I'm a flawless modeler, but because I always cast a critical eye over the mesh and catch my mistakes as soon as they happen--failing that, I manually get in there and fix the problem when I find it.

That being said, you can use the the Select Orphans tool to catch those edges and duplicate points automatically. However there are cases where you have a two overlapping points that are attached to two separate faces, and for that the merge points tool generally does its job.

A face is the same thing as a polygon. If you know the difference between concave and convex shapes, then that's all there is to know to tell if a face is concave or not. You don't have to force the triangulation of all faces if they behave properly already, since that's the way they'll export as well. For 3D printing, the slicing software is usually flexible and can handle some pretty bad models, I imagine because they use volume-based operations to slice it and "fill in the gaps" when something's wonky.
« Last Edit: August 23, 2013, 09:03:25 am by Raxx »
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