What am i doing wrong? Simple High to low poly...

gibbonuk

Hi im Andy, and new on here so helloooo :poly121: and really hoping you can help me get past this massive wall ive hit.

Ive been teaching myself modelling for a while now and getting on fine with some simple stuff, more so ive been doing some rocks and boulders game assets as i like playing around in UDK and Leadwerks.

The simple process for doing my rocks has been as follows:

1. Make highpoly rock in sculptris and save as obj
2. using meshlab i lower polys down to a reasoble amount (200 - 400)
3. unwrap the low poly and texture it.
4. using Xnormal i bake normal map and ambient occlusion map which i add to the diffuse.

And they come out ok, i then go on to do a bit more like detail texture normals etc.


So..
I want to create some modular stone wall sets and Ive tried a few times to do this but seem to failed everytime and give up, but over these last few days ive give it a real go.. and unfortunatly im pulling my hair out as it appears my learning process is going backwards!

To do this i....

1. Created a basic stone shape in wings 3d
2. inported to sculptris and detailed it in.
3. I then made copies of that stone brick and made a wall out of it
4. Once i had a high poly wall mesh in sculptris i exported as an obj
5. Opened it in meshlab and made a low poly version
6. Unwrapped the low poly
7. Run into problems as below....

So i go on to try do my normals and ambient occlusion maps in Xnormal!!
My result are below, what am i doing wrong, or missing? :poly118:

1. Highpoly Mesh

2. Low Poly Mesh

3. Resulting Normal map (whats causing all the messy bits?)

4. Ambient Occlusion Map (Again...what a mess???)

5. Resulting Low Poly with normal map (messy!)

6. Resulting Low Poly with AO map (really messy!)


Hope you can help me i really really want to nail this.
Thanks
Andy

EarthQuake

Well,

A. where the lowpoly bricks are touching/intersecting, you're going to get errors projecting the detail, that should explain all of the problems in those areas. Generally when baking a mesh like this you need to "explode" or seperate each chunk in both the high and the low, so you dont get intersecting problems. Alternatively you could model the lowres model as a solid mesh, instead of a bunch of intersecting meshes, this would also cut down on polygon usage and give better texture useage as well.

B. You've got all sorts of general areas not near the intersections, I imagine these would be due to:
1. Incorrect ray distances, your rays aren't expanding out far enough to cover the mesh
2. Possibly uv corruption issues?

Now having said all of this, why are you modeling this brick by brick? This sort of thing would generally be handled with a tiling texture, as modeling every brick in a wall is going to be much too performance intensive.

Mark Dygert

Yep, looks like you UV'ed the high, polycrunched it or optimized it somehow to make your low poly and it screwed up the UV's? I see in your process that you unwrapped it after crunching it, but it doesn't look that way, maybe you unwrapped it to a different channel than your baking app is out putting to?

Re-UV map the low, or like EQ said project the high onto a simple plane, check your ray depth bla bla bla.

gibbonuk

EarthQuake:
thanks for your reply, and i didnt realise that by having the models touching / interecting each other would cause errors, which is the only thing ive done here different as apposed to my other models where i have had success.

The reason for the black areas that dont make sense might be down to me playing with the ray settings in Xnormal after getting poor results first time round.

And the reason for doing it brick by brick is obviosuly somthing of a learning curve im on. I have upto now tryed sculpting a rock wall as one piece but just failed to get it to look good, mainly because of the creases that give the wall that "brick by brick" effect, just couldnt nail it. :poly118:

But thank you for you comments and ill go back and try things a little differently.

So firstly to get rid of projection errors in this case i would need none of the low polys to touch or intersect each other?

Mark Dygert:
Thanks also for your reply, although i can 100% say that is the low poly unwrapped, at no point did i open the high poly in my unwrapper and i definatly would have noticed as being high poly would have bogged the uvmapping software down.

One thing i would like to know more about or how i could do is projecting the high to a plane with the software tools i mentioned above, if not is there any free / cheap ones about to do it with, i know of blender but really unfamilier with its interface and usage.

Thanks again for the replies, love to learn!

Andy

SpeCter

Not really sure, but doesn´t xNormal have an built in Cage Editor? If yes you can do it in there..

gibbonuk

Hi Specter, is this yes to the projecting the high poly to a plane?

Ive had a look and yes Xnormal does have a built in cage editor, unfortunatly for me i dont really know much about the cages nor editing them, so ill be in search of tutorials now

Thanks
Andy

SpeCter

Yes you can use the Cage Editor for projecting the high poly to a plane.
Basically you place the plane right in front of your highpoly and let the cage reach behind your highpoly.

Heres a little picture to show(i know it´s kinda messy, i hope it helps regardless of that)

This is Sideview.



Actually the plane can be nearer to the highpoly,but you should get the point.

You should really read into using cages they can be a real lifesaver if you don´t get the right results with raydistances only.
The cage helps to get the rays where you want them to go.

gibbonuk

Hi Specter, thanks alot for your reply, just watched the turorial on xnormals website about the cage editor and your diagram shows true to how this can be done, definalty going to play around with that.

Thanks for the help, this appears to be a very good and helpful forum!

Andy

SpeCter

Polycount is the best nothing less

Just keep practising with xNormal and you will get the hang of it faster then you might think