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General => Open Discussion => Topic started by: yossam on March 31, 2015, 03:09:25 pm

Title: Map test
Post by: yossam on March 31, 2015, 03:09:25 pm
Do you see a difference between the rocks? They are the same object, just different maps in the displacement slot. One uses a bump map...........the other a displacement map (which I have never run across before). The maps are different just by looking at them. And no, it's not a normal map. I got one of them too.
Title: Re: Map test
Post by: TheBadger on March 31, 2015, 03:32:08 pm
The one on the right is displacement map, I guess. I think the one on the right looks slightly better. Am I correct the one is displacement map?
Title: Re: Map test
Post by: fleetwood on March 31, 2015, 03:48:21 pm
Since "real" displacement casts a corresponding shadow beyond an object and bump doesn't cast shadows beyond an object, it seems the more simple ground shadow on the left would indicate the bump mapped one.
Title: Re: Map test
Post by: yossam on March 31, 2015, 03:58:25 pm
The one on the right is bump mapped, the left is displacement mapped. I'm still trying to figure this out. I got a few more to play with. Will post the results.  ::)
Title: Re: Map test
Post by: PabloMack on March 31, 2015, 04:02:42 pm
The viewer-relative orientation of the two objects is different enough that it is difficult to judge which one is which. If there is a lot of geometry in the base object then there isn't going to be much difference when bumps/displacements are small relative to the geometry. I think I can see some displacement near the top right of the left object that is not there in the right object but rotation might account for it.
Title: Re: Map test
Post by: yossam on March 31, 2015, 04:44:47 pm
Put both objects at origin so the view would not affect the outcome. Same as before............which is which?
Title: Re: Map test
Post by: Kadri on March 31, 2015, 05:05:34 pm

Not sure but i think other then kinda different looking image map and because of this,getting a different bump mapping effect there isn't much difference.
You are using a different image for bump mapping basically. Only if you don't use ray tracing for objects you will get real displacement.
So the question which one is different is kinda mood.


Title: Re: Map test
Post by: Oshyan on March 31, 2015, 05:11:09 pm
Are you talking about the difference between applying 2 *different maps* (from an external source) in the *same way* in Terragen? I.E. image 1 - bump.jpg - and image 2 - displacement.jpg - and applying them both with e.g. a Default Shader? OR are you referring to applying the same source image, but for one render using Raytrace Objects (only renders bumps, no displacement), and the other with Raytrace Objects off (displacement will work)? I assume you mean the first thing, in which case I would wonder what the difference between these maps actually is, where they came from and what they're intended for. I would normally guess that a Displacement Map intended for another app would be lower resolution than a Bump Map simply because Bump Maps can portray finer scale detail better than large scale detail, and at a lower render time cost than fine scale displacement. I don't think for Terragen use that it is particularly useful to have both, I would just favor the one with the greater detail. A *normal map* and *vector* displacement map are both different things and would have to be handled totally differently.

- Oshyan
Title: Re: Map test
Post by: PabloMack on April 01, 2015, 07:58:15 am
Quote from: yossam on March 31, 2015, 04:44:47 pmPut both objects at origin so the view would not affect the outcome. Same as before............which is which?


I can see some displacement outward along normal in Maptest2a relative to Maptest2. It's not a lot but noticeable.

Was it the same (UV) map that was used in two different ways?
Title: Re: Map test
Post by: yossam on April 01, 2015, 02:23:48 pm
They are two different maps, one labeled "bump", the other labeled "displace". I tried to post but keep getting error message about being too big. They are 4k maps but the file size is not showing over the limit. I'll keep trying.
Title: Re: Map test
Post by: Dune on April 02, 2015, 02:42:18 am
One in each post maybe. Or reduce into jpg.
Title: Re: Map test
Post by: yossam on April 02, 2015, 05:33:19 pm
Had to do a screen grab............they would not post regardless of what I saved them as. Strange........... :o
Title: Re: Map test
Post by: Upon Infinity on April 03, 2015, 02:04:45 am
I came across a similar conundrum while I was doing all the modelling I've been doing lately.  I actually at first panicked, thinking I was using the wrong maps.  I came to the conclusion that different maps simply have different uses for different programs.  A displacement map first and foremost is for, well, displacement.  I believe bump maps were for before many programs could do actual displacement or for just a different effect.  Personally, I prefer the bump map as it gives finer detail (and it can also do displacement)  There is a difference, to be sure, though it is subtle..  I put a small video together of me flipping between the two images.  I think for your experiment, though, that you should have dropped the colour map so the effect could be seen easier.

It could also be that some renderers support not only displacement maps, but also bump maps, as well, giving you not only the displacement (which is rougher) but also the fine (fake) detail of the bump map.

https://www.youtube.com/watch?v=8C_YiFIQnyA&feature=youtu.be
Title: Re: Map test
Post by: yossam on April 03, 2015, 09:55:24 am
Without the diffuse................
Title: Re: Map test
Post by: j meyer on April 03, 2015, 11:34:10 am
You still didn't tell us if you rendered with ray trace objects on or off.
My guess would be ray trace on.
The other thing is you don't show the object without displ or bump map.
Makes the guessing not easier.
The look of the last pics seems to indicate that your model might have no
normals,thus the facetted appearance.(normal smoothing doesn't work without
normals)
Judging from the pics of the maps the displacement is meant to do the big
shapes that would alter the look of the undisplaced object.This does only
work with ray trace off in TG as others mentioned already.
The bump map is for the fine detail that wouldn't cause visible changes in the
outer shape of the object.
Depending on the program you could use the normal map for the latter as well.
Bump or normal mapping as a last layer on a displaced low or mid poly model
that's a pretty common approach.Works for many apps and game engines etc.

Title: Re: Map test
Post by: Dune on April 03, 2015, 11:47:37 am
Regarding normal maps, why are they blue? If you use them as bumpmap, better make greyscale and increase contrast.
Title: Re: Map test
Post by: PabloMack on April 03, 2015, 12:33:12 pm
Quote from: j meyer on April 03, 2015, 11:34:10 amThe look of the last pics seems to indicate that your model might have no normals,thus the facetted appearance.(normal smoothing doesn't work without normals)


I don't think this makes sense. If your object has polygons then those polygons have normals. It might be more complicated to compute what the normal is if the vertices of a polygon were not co-planar but there is still a normal.
Title: Re: Map test
Post by: j meyer on April 03, 2015, 01:16:56 pm
PabloMack - some apps don't export normals to keep the file size reasonable.
                 In most modeling packages and modelers you won't notice,because
                 they generate the normals automatically.TG does not.That why it's
                 noticeable.
                 Recently talked about it here:http://www.planetside.co.uk/forums/index.php/topic,19091.30.html
                 Just scroll down a bit.
Edit: sorry for the not working link,don't know what happened.


Ulco - there is a difference and some apps prefer normal maps others bump maps.
         Don't know why it evolved like that.Maybe the wikipedia does.
Title: Re: Map test
Post by: yossam on April 03, 2015, 02:35:38 pm
This is with no maps, nada, ziltch, 0......................
Title: Re: Map test
Post by: Dune on April 04, 2015, 03:19:16 am
Did you set 'use smooth normals' in TG? What if you take this through Poseray, calculate smooth or at least say 60ยบ normals, export and texture procedurally in TG?
Title: Re: Map test
Post by: PabloMack on April 04, 2015, 08:23:38 am
Quote from: j meyer on April 03, 2015, 01:16:56 pm
PabloMack - some apps don't export normals to keep the file size reasonable...


I guess there are two benefits from having the normals specified in a separate
data structure. One is so that the program receiving the object doesn't have to
deal with computing them. The other is so that they could actually be computed
to point in a direction other than what the geometry would imply. But the practice
of having to precompute values that are already implied in the data structure is
not very efficient. As you say, some applications don't include it to save file space.
Since this information is implied in the geometry then it is already there but must
be computed to make it available. I guess the ultimate goal here is that a displacement
map needs to relate how much displacement there is going to be using a UV map
to scale the displacement in the normal direction by an amount in a UV mapped
image. We are talking about a data structure now that needs a lot more information
than just normals. But I guess you are telling me that, even if you specify a UV
displacement map, if the normals that are referenced in the UV displacement map
are not provided as a separate data structure (internally in the object) that TG
does not compute them from the geometry so that the UV displacement map
will be ignored?
Title: Re: Map test
Post by: j meyer on April 04, 2015, 11:04:32 am
yossam - no maps at all looks the same as the one with displ map only.That's strange.
             The displ map should have an effect rto on or off.Occasionally one has to crank
             up the value quite a bit.Other than that I've no idea at the moment.
             Is the rock a ZBrush made object?
             Anyway,you can use poseray to add normals.

PabloMack -
QuoteBut I guess you are telling me that, even if you specify a UV
displacement map, if the normals that are referenced in the UV displacement map
are not provided as a separate data structure (internally in the object) that TG
does not compute them from the geometry so that the UV displacement map
will be ignored?

Nope,displacement maps and such should still work as expected.
Title: Re: Map test
Post by: Upon Infinity on April 05, 2015, 05:14:41 am
Quote from: Upon Infinity on April 03, 2015, 02:04:45 am
It could also be that some renderers support not only displacement maps, but also bump maps, as well, giving you not only the displacement (which is rougher) but also the fine (fake) detail of the bump map.


I hate being right all the time...   ;)

https://www.youtube.com/watch?v=rzXNZkEoTAk
Title: Re: Map test
Post by: yossam on April 05, 2015, 01:00:47 pm
Here is what I could find out about the workflow for the rocks. To start they used photogrammetry to construct the mesh. Autodesk ReCap360 to Zbrush for more modeling, from Zbrush to Mudbox for texture painting and retopology. I am not that familiar with any of the software mentioned..............maybe that could be part of the problem.  ???
Title: Re: Map test
Post by: Dune on April 06, 2015, 03:22:22 am
This kind of rock is fairly easy to make, also in LW. Texture it procedurally and you're fine. And I think with some clever PF's you can build these shapes within TG with displacable cubes, or even fake stones or a rock population.
Title: Re: Map test
Post by: j meyer on April 06, 2015, 11:20:49 am
As for the facetted look it could be caused by ZBrush not exporting normals,but I don't
know,if mudbox does export normals or not.The effect could be caused by a wrong
creasing also.Both can be fixed with poseray.To change the crease settings you have
to change the creasing value in poseray before you import an object as far as I know.
Maybe more than one try required.
Still no idea why the displ map seemingly doesn't work,sorry.