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Student Thread - TiagoLPS

35 posts in this topic

Posted

Ok so i used decimation master on the chair, and it reduced the polycount from ~600.000 to ~100.000  would that be enough?

For use in game I would say to aim for less than 1,000 triangles. To go from something like 600,000 to 1,000 with decimation master it can be helpful to do it in two or more rounds where you first decimate down to say 5-10% of the original and then go to your target geometry. It's likely though that you'll have to use a combination of decimation master and modeling the low poly by hand to get a good fit. The other option is to just model the whole thing by hand. Up to you, but for me at least starting with decimation master and cleaning it up is a time saver, and that's important because I find creating the low poly to be the most time consuming (and important!) step of the whole workflow.

I put together a few examples of what you're trying to do. Here in the first one we're trying to make a good low poly mesh that captures the high poly mesh efficiently with the fewest vertices. This will mean sometimes being on the 'inside' of the high poly, sometimes not. After UV-unwrapping the low poly mesh and completing any changes you want to make to it, you can now create a 'cage' for the low poly. This model is used to calculate the angle and position where rays are simulated in the baking process and should be on the outside of the high poly at all positions. The easiest way to make this is by using the Push modifier, which moves a vertice along the normal vector. Some manual tweaking is necessary at times but Push does most of the work for you.

9cmJxGA.jpg

Now with the low poly and cage, I was able to take the painted high poly (left) and bake the polypaint to a texture (middle) and then use that texture on the low poly model within Max (right). 

YWOd6VY.jpg

 

 

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Posted

So in this case I can use the lowpoly from 3D max I made before sending it to zbrush

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Posted (edited)

One question though, while UV unwrapping the low poly, can I overlay, for example, the back part and the front part of the back of the chair, to save space, or should I keep it all separate? If I have to keep all separated, its going to be a little hard to fit everything in isn't?

This is the lowpoly btw:

Untitled_1.png

Edited by TiagoLPS

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Posted

One question though, while UV unwrapping the low poly, can I overlay, for example, the back part and the front part of the back of the chair, to save space, or should I keep it all separate? If I have to keep all separated, its going to be a little hard to fit everything in isn't?

This is the lowpoly btw:

Hidden Content

Sure, if you have identical (or even similar) surfaces you can reuse the baked UV space. But I'm not sure the front and back of your chair are a great candidate for that since there appear to actually be some differences there.  A place you could use symmetry would be the legs, since it looks like your right and left sides are exact copies. In the low poly model you use to bake, only use one side. Then, for your actual low poly copy the UV mapping to the other. And, I wouldn't be to worried about fitting everything for the chair into one UV map anyway, it doesn't have all that much surface area relatively. 

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Posted (edited)

Finished unwrapping the UVs :)

UVWs_Nordic_chair.png

Edited by TiagoLPS

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Posted

Finished unwrapping the UVs :)

Hidden Content

Alright, we can make a lot of improvements here. What you're doing is essentially breaking every flat surface into it's own UV 'island'. While that will guarantee no stretch of the textures, it doesn't necessarily give you the largest pixel density, and also makes it very hard to create a texture with a smooth appearance that lacks visible seams at the edges. Do you understand that last point? If you have two isolated UV islands placed on an image, and they are then rendered sharing an edge in 3D, the texture will appear to be torn between the two faces. There ARE ways to get around that to an extent, but it's better to leave faces with exposed edges together in an island if the UV distortion isn't too great. 

This video has some decent animations to help get the visual concept of what you want to be aiming for when you unwrap: https://www.youtube.com/watch?v=iIvTUDgaXik

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Posted

Alright, we can make a lot of improvements here. What you're doing is essentially breaking every flat surface into it's own UV 'island'. While that will guarantee no stretch of the textures, it doesn't necessarily give you the largest pixel density, and also makes it very hard to create a texture with a smooth appearance that lacks visible seams at the edges. Do you understand that last point? If you have two isolated UV islands placed on an image, and they are then rendered sharing an edge in 3D, the texture will appear to be torn between the two faces. There ARE ways to get around that to an extent, but it's better to leave faces with exposed edges together in an island if the UV distortion isn't too great. 

This video has some decent animations to help get the visual concept of what you want to be aiming for when you unwrap: https://www.youtube.com/watch?v=iIvTUDgaXik

I get it. So instead of doing every flat face by face, I  should do whole blocks? what part would work, and what parts wouldn't in this chair? 

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Posted (edited)

I would suggest these islands to start with:

  • one for each leg (4)
  • one for each brace between the legs (2)
  • one for the seat 
  • one for the seat back 
  • possibly one for the head rest, or combine it with the seat back

For each one you'll want to create an island similar to what is shown for the box in the video. Try to hide the seams in places that are less likely for the player to see, so on the inside of the chair leg for example. This isn't always possible but should be done when it can.

By the way, how many polys do you have currently? If it's not too high, you might consider chamfering the edges in some places to give a smoother result in the end. 

Edited by Escha
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Posted (edited)

I would suggest these islands to start with:

  • one for each leg (4)
  • one for each brace between the legs (2)
  • one for the seat 
  • one for the seat back 
  • possibly one for the head rest, or combine it with the seat back

For each one you'll want to create an island similar to what is shown for the box in the video. Try to hide the seams in places that are less likely for the player to see, so on the inside of the chair leg for example. This isn't always possible but should be done when it can.

By the way, how many polys do you have currently? If it's not too high, you might consider chamfering the edges in some places to give a smoother result in the end. 

Just one thing about the seat, it's separate planks :P also all edges have been chamfered "I think" 

Edited by TiagoLPS

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Posted

Just one thing about the seat, it's separate planks :P also all edges have been chamfered "I think" 

So are you saying there are surfaces between the planks that aren't really seen by the player, covered up by the other planks? You should connect the edges of the planks if so, so that you don't have big hidden surfaces. 

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Posted

So are you saying there are surfaces between the planks that aren't really seen by the player, covered up by the other planks? You should connect the edges of the planks if so, so that you don't have big hidden surfaces. 

Ill take a picture once I can.

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Posted

So are you saying there are surfaces between the planks that aren't really seen by the player, covered up by the other planks? You should connect the edges of the planks if so, so that you don't have big hidden surfaces. 

 

Untitled_1.png

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Posted

Oh my.. That's an awfully big waste of polygons. You would usually stick those cracks in to a texture map.

Oh man... got to rework that seat then.

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