***BAD BUG (Octane accuracy)...PAY ATTENTION!***

[nildoe]

Guys Id like to know something regarding Units...
what do you consider to be the correct way to work

I live in a metric country, but since a long time i've been told to never change the SYSTEM UNITS of MAX, ie, leaving it at inches but work with display units instead, changing that to meters or centimeters...working like this i've never had issues.

Working in Octane will that affect the light and the rendering quality of the image?

What i have noticed however is whenever i wanna work with Glu3d for example...im forced to change the system units to meters otherwise my objects just seem to big for the simulation to work properly...

Nildo

[wxyz]

What size system units were people using on the problem renders?

[hadouken]

the unit size you should choose depends entirely on the scale of your intended scene. If you were going to do a overhead bird pan of an ocean then it would be silly to use system units in centimeters since you'd quickly reach 99999999999units and max would freak out. Conversely, it would be silly to use meters if you were modeling a lego set or a bird house. The whole point of system usnits afaik is to keep max in the same ballpark of your scale so that it doesn't have to calculate in logarithmic scales like .000000000000000001 or 100000000000000000000. In order to prevent max from freaking out you need to tell it in what vicinity you'll be working in so it can stay working within 3-4 decimal places of your scale...that's the gist of it and I hope it makes sense.

Whenever I need to do precise modeling but need that model in a big scene then I simply build the precise model in a scene with cm or mm and when I'm done, merge it into the final archviz scene that may be in inches or feet/meters. if the scale is off when I merge it in then it doesn't matter since I already built it under precise conditions. I just scale it to the correct scale and reset xform and i'm done. As soon as I saw that image in the first post with 500000 10000000 cm i was shaking my head. That's ridiculous. If you need that many cms, then you shouldn't be using cms.


That being said; I'm very curious to see how octane talks to max's unit scale and how changing max's system affects octane-if at all. Can a team member explain? I don't own the max plugin yet but plan to get it...maybe today since I just got my tax return

[gabrielefx]

the unit size you should choose depends entirely on the scale of your intended scene. If you were going to do a overhead bird pan of an ocean then it would be silly to use system units in centimeters since you'd quickly reach 99999999999units and max would freak out. Conversely, it would be silly to use meters if you were modeling a lego set or a bird house. The whole point of system usnits afaik is to keep max in the same ballpark of your scale so that it doesn't have to calculate in logarithmic scales like .000000000000000001 or 100000000000000000000. In order to prevent max from freaking out you need to tell it in what vicinity you'll be working in so it can stay working within 3-4 decimal places of your scale...that's the gist of it and I hope it makes sense.

Whenever I need to do precise modeling but need that model in a big scene then I simply build the precise model in a scene with cm or mm and when I'm done, merge it into the final archviz scene that may be in inches or feet/meters. if the scale is off when I merge it in then it doesn't matter since I already built it under precise conditions. I just scale it to the correct scale and reset xform and i'm done. As soon as I saw that image in the first post with 500000 10000000 cm i was shaking my head. That's ridiculous. If you need that many cms, then you shouldn't be using cms.


That being said; I'm very curious to see how octane talks to max's unit scale and how changing max's system affects octane-if at all. Can a team member explain? I don't own the max plugin yet but plan to get it...maybe today since I just got my tax return

you are right.
I haven't any problem to design a chair model in centimeters and then import it in a new scene in meters or kilometers using Vray.
Try to download my test scene and merge it in a scene where the scale is set in meters. You will get the same accuracy error....using Octane for Max.

[gabrielefx]

Yes, a real problem!

This is not a problem. You have to work with proper unit scale.

try to merge my test scene in a new one with scale set in meters....

[face]

Hm, i don´t know how Max handle units.
I think, a vertex which lies on 1,1,1 can be mm, cm or others, units are only for better working if you merge scenes or construct meshes.
We had this discussion for some time in the free plugin forum.
If you get the mesh data the position for the vertex above is 1,1,1 whatever your unit is.
Octane interpret this 1,1,1 as meter and that is the problem.

An example.
Say a room have 50m² and the vertex above is on one edge so the vertex lies on maybe 50,50,50 if you work in meters.
If you work in cm, the vertex lies on 5000,5000,5000. Octane interpret this as 5.000 meters because 1 is one meter.

We have integrate a listbox in the plugins where the user can set the unitscale and the plugin has rescaled all values to resolve some issues.
The misunderstandings then came like this, "I work in mm, changed the listbox to mm, but i get artefacts".
And this can be correct, if you are working in mm you must set a vertex at location 1mm,1mm,1mm with 0.001,0.001,0.001 because Octane only knows meter and the plugin scaled the mm with factor 1000 to meter.
The other side says, that´s incorrect because i set a vertex at 3,3,3 which should be mm. The plugin also rescale with factor 1000...

The best way to solve scaling issues is to think in values, not units. Units are messy.
If you think in values you will know, in a scene which has values like 5000 or higher you can get artefacts.
Simple but effective...

face

[gabrielefx]

Hm, i don´t know how Max handle units.
I think, a vertex which lies on 1,1,1 can be mm, cm or others, units are only for better working if you merge scenes or construct meshes.
We had this discussion for some time in the free plugin forum.
If you get the mesh data the position for the vertex above is 1,1,1 whatever your unit is.
Octane interpret this 1,1,1 as meter and that is the problem.

An example.
Say a room have 50m² and the vertex above is on one edge so the vertex lies on maybe 50,50,50 if you work in meters.
If you work in cm, the vertex lies on 5000,5000,5000. Octane interpret this as 5.000 meters because 1 is one meter.

We have integrate a listbox in the plugins where the user can set the unitscale and the plugin has rescaled all values to resolve some issues.
The misunderstandings then came like this, "I work in mm, changed the listbox to mm, but i get artefacts".
And this can be correct, if you are working in mm you must set a vertex at location 1mm,1mm,1mm with 0.001,0.001,0.001 because Octane only knows meter and the plugin scaled the mm with factor 1000 to meter.
The other side says, that´s incorrect because i set a vertex at 3,3,3 which should be mm. The plugin also rescale with factor 1000...

The best way to solve scaling issues is to think in values, not units. Units are messy.
If you think in values you will know, in a scene which has values like 5000 or higher you can get artefacts.
Simple but effective...

face

Ok...
If I want to draw a large building in meters and fill it with furnitures drawn in the past with various units (mm., cm., inches) and then I want to create a flythrough animation that goes the various rooms without stop the camera (long sequence)...I can't to do it.
Because in the first room all furnitures will be ok without artifacts, I'm near the origin.
Moving the camera 50meters away I will notice geometries with broken triangles (not welded)

[face]

Ok, you´re right,
have tested it with a plane which have a uv length from 50 units, also -25.0/25.0 on x and y,
a box which has a value from 0.001³ units with 100 subdivisions on each axis and is positioned on one corner.

I can export the scene with a scaling factor between 0.001 and 100000 and the issue is ever existing.
At 0.001 the aperture of 0.01 is to big so i get a blurred result, but the area which is in focus, is also breaked.
Values greater then 2000 gives me only the background, the mesh is, i don´t know, breaked in tiles which the camera can´t see.
The camera position/target is also scaled so you wouldn´t see on a correct scene that the scaling is an other.

It has also nothing to do with some scaling issues.

face

[hadouken]

well that sucks

[gabrielefx]

I was wrong.
It's not an Octane bug.

vray, vray-rt, mentalray, iray, produce the same results.

I did another experiment: I modeled with Rhino two cubes of 10x10x10cm distant 10 kilometers to each other.

the first one was meshed well, the second one with approximate meshes.

But what happens if I create a tree 100 kilometers distant from the origin?