Vertex Count & Light Map Vertex Count

[juoolz]

Hi all,

So as the heading suggests I have two questions that relate to each-other.

1. The vertex count I’m getting between a “hard edge cube” and a “smoothed edge cube” is 24 - 23. This seems a little strange or is this correct. Note: I have not added light maps to either of these two cubes and their UV layout is identical. (image attached)

2. I have noticed that as long as the Light map UVs are identical to the Base UVs no extra verts are calculated. However the more deviation between the two (i.e more UV splits made to the LightMap UVs) the more the vert count increases.

As you can see this is causing some problems when planning my models for UE4. So… How is smoothing calculated, how dose it effect vert count and what is the relation between the base UVs and light map UVs?! Any info on guidelines would be awesome.

Thanks again

J

[Tim_Hobson]

Hi Juoolz,

This does seem a little odd and I’ve not been able to reproduce this on my end. I took and made three separate meshes for my test case in 4.4.3.

1 - Cube with 8 smoothing groups 1 for each face
2 - Cube with 7 smoothing groups with the front and top in the same smoothing group
3 - Cube with 1 smoothing group with all faces in the single smoothing group

My result was as expected with 24 vertices and 12 triangles.

I only had a single UV.

Here is my test FBX with all three cubes.
Can you test this and see if you’re getting the same results? Can you also tell me which version of the engine are you using currently?

Thank you!

Tim

[juoolz]

Hi Tim,

Your files worked.

I checked all export and import setting and I believe its all correct!? See images attached…FBX is also 2013 and I’m using 4.4.3

Here is a link to my files if you want to give them a try. Dropbox - Error

I never mentioned before that I use maya 2014. Also in the image attached you can see both cubes with smooth edge visibility on. Im still getting 23 on the smooth edge cube.

Cheers

J

[Tim_Hobson]

We’ve not been able to reproduce this vert count with our Maya (2013).

Can you list the repro steps for creating your smoothed edge in Maya up to the export.

I’ve tried doing some other methods of smoothing in Max to see if I could replicate and even imported and exported your mesh with the same results.

At this point, I want to narrow down if this is a bug with UE4 or possibly something on Maya’s end.

Thank you for your help!

Tim

[juoolz]

Hi Tim

I made a quick video running through the steps. You can find it in Dropbox - Error

Also if you want feel free to Skype me if that speeds up the process! my Skype name is “juoolz”

[Tim_Hobson]

I had Eric give your video test a shot and he was still not able to get the 23 verts.

He made three cubes in his initial test:
1 - No Smoothed edges
2 - single smoothed edge
3 - all edges smoothed

the results were that there were 24 verts for all three.

Here is the file: https://www.dropbox.com/s/crlajm1te1ac1qj/Cube_Maya_Test.fbx?dl=0

In the next test he made a cube with a single smoothed vertex. This resulted in three faces smoothing and vertex count of 22.

Here is the file: https://www.dropbox.com/s/sphr03og9sqm57n/Cube_Maya_Test_2.fbx?dl=0

Now to take a moment and go back to the original issue with regards to UVs and lightmaps.

I didn’t see a difference between your UVs and I’m not getting a difference on these that I can see either. With regards to how smoothing works. The vertex normal is what is changing here. you can take a look at the second asset above and see how the vertex normals are aligned for the smoothed edge vs the hard edge.

You shouldn’t have an issue with your mesh here I believe.

Tim

[juoolz]

Hi Tim unfortunately the mystery continues.

All your files imported in to unreal perfectly! However I took the Cube_Maya_Test_2 and simple reExported it using my Maya2014 with FBX format Maya2013 and…they imported with two different vertex counts!? I made a quick vid again to demonstrate. Dropbox - Error

I should also mention when exporting and importing your FBX and my reExported FBX in to Unity they both import 1to1 the same…dont know if that helps in anyway.

Also I work on a mac if this makes a difference.
Processor 2,4 GHz Intel Core i7
Memory 8 GB 1600 MHz DDR3
Graphics NVIDIA GeForce GT 650M 1024 MB
Software OS X 10.9.4

J

ps hope I’m not making your life to painful

[juoolz]

Right Iv continued playing around and discovered that During import I have to select “import normals” with my file…but not with yours?! see video Dropbox - Error

[Tim_Hobson]

Thanks for the vids! I’m still not exactly sure what’s going on here but I’ll try some variations on imports from Max and Maya today and see if I can get an organized approach to this and see what’s going on.

Thanks for all your help! It is greatly appreciated!

Tim

[Tim_Hobson]

With Calculate Normals - 24 is expected as this is not importing any information from the FBX. UE4 is calculating the normals itself instead of relying on the FBX information.

I did manage to get a cube to import as 23 verts though from Max. I set up a cube > Exported and only used Triangulate and Smoothing Groups > Import into UE4 > Normals: Import Normals and Tangents.

I spoke with one of our tech artist and he said this is expected behavior. For instance if we look at the cube with a smoothed corner (the three faces smoothed) we see 22 verts. This is welding that vert to calculate the smoothing. This is the same for a sphere where it may be one number in Max/Maya but when imported the vert count will be radically different because of welded and non-welded edges. If the edge is not smoothed each vert is broken apart and not welded in this instance.

This is all expected behavior.

To go back to your original question:

how dose it effect vert count and what
is the relation between the base UVs
and light map UVs?

You will not have to worry about this affecting your UVs and how the texture is handled in this instance.

Thanks for your patience and helpfulness!

Tim

[juoolz]

Hi Tim not a problem.

Tim I know this is off topic and prob not the place to post this question …however I’m trying to get my teeth in to (and get my head around) creating Materials/Shaders. Are there any resorces that really dig deep! Information that really shows practical and theoretical examples.
I should mention I have been through the UE4 documentation and that has given me a good start but then you stumble across someone doing something awesome…and well realise you have no idea what your doing or whats actually possible

Any and all leads would be fantastic.

[Tim_Hobson]

There is a lot with Materials I’m still learning. I am no real expert in that area per se. There are plenty of users on the forums who may have a much wider wealth of knowledge than I do though.

For instance, Eric Ketchum (one of our Support Engineers) is great with materials and general VFX.

mAlkAv!An has, to me, been the Materials guru on the forums. He’s always posted a wealth of knowledge when someone gets stuck.

Eric has mentioned William “Bill” Kladis on numerous occasions. There is a lot of information in his UDK materials books that will carry over, but of course some information is outdated based on the rendering system that UE4 uses now.

If you post in the General Discussion section of the Forums there are probably a long list of information people can link you to to learn materials much better!

Tim

[juoolz]

Awesome thanks again!

J