Hi,

last time I used houdini I noticed that when I am exporting an object there are some problems when the object was moved in object level (world). As long there is a translate in the object transform you will get problems when exporting the model and importing it in an another program. The model will be translated differently in the other app.

The only solution to this it seems is to zero the translates in object level and move the primitives in context level with a transform node with the same amount.

I am missing something? This means you cannot move objects in object level, otherwise when you export you will get some problems. Is there a solution to this? How do you build whole worlds, when you can only move in context level? Thanks in advance.

houGenie
I am missing something?

probably setting Transform parameter on ROP Geometry Output from None to Into World Space

but Alembic ROP should keep the hierarchical transform so I'm assuming you are not exporting alembics


personally I try to avoid transforms at object level or at least be mindful when using them

i just tested a torus being moved up 1 unit in object level.

- FBX
- Houdini in meters, Max in cm.
- imports fine…(leave size out of it)…the torus is 1cm up.
- if Max was in inches….the torus is 0.394 up…which is sorta correct (if you pretend the 1 in Houdini was 1 cm)

vusta
i just tested a torus being moved up 1 unit in object level.

- FBX
- Houdini in meters, Max in cm.
- imports fine…(leave size out of it)…the torus is 1cm up.
- if Max was in inches….the torus is 0.394 up…which is sorta correct (if you pretend the 1 in Houdini was 1 cm)

Houdini doesn't use units. It's 1 ‘one’ up.

jsmack

vusta
i just tested a torus being moved up 1 unit in object level.

- FBX
- Houdini in meters, Max in cm.
- imports fine…(leave size out of it)…the torus is 1cm up.
- if Max was in inches….the torus is 0.394 up…which is sorta correct (if you pretend the 1 in Houdini was 1 cm)

Houdini doesn't use units. It's 1 ‘one’ up.

Hip File Options
Unit Length

The length in meters of one Houdini unit. This value is used by some unit-specific DOPs parameters.

Unit Mass

The mass in kilograms of one Houdini unit. This value is used by some unit-specific DOPs parameters.

Note

Unit time is always one second.

The units values only affect the default values of certain constants in DOPs, and the depth of field in mantra. They do not affect geometry position values on import/export.

pretty sure I can read…

you don't have to automatically underestimate my intelligence.

vusta
i just tested a torus being moved up 1 unit in object level.

- FBX
- Houdini in meters, Max in cm.
- imports fine…(leave size out of it)…the torus is 1cm up.
- if Max was in inches….the torus is 0.394 up…which is sorta correct (if you pretend the 1 in Houdini was 1 cm)

Did not try with fbx (cannot import them because there is an error in max). Try please with obj. World transforms in object level are ignored.

houGenie
Did not try with fbx (cannot import them because there is an error in max). Try please with obj. World transforms in object level are ignored.

so I assume you tried this and it didnt work for you?

tamte

houGenie
I am missing something?

probably setting Transform parameter on ROP Geometry Output from None to Into World Space

yes, in fbx it works. but not in obj! the world transform of an object is ignored in obj it seems.

houGenie
yes, in fbx it works. but not in obj! the world transform of an object is ignored in obj it seems.

with Transform set to Into World Space?

for me it seems to correctly export .obj in the world space

tamte

houGenie
yes, in fbx it works. but not in obj! the world transform of an object is ignored in obj it seems.

with Transform set to Into World Space?

for me it seems to correctly export .obj in the world space

how do you export in obj? you can only export in fbx in object level. i exported an obj with the file node in the SOP context.

as mentioned ROP Geometry Output SOP
or you can also use Geometry ROP

both of them have Transform parameter that you can set to Into World Space

tamte
as mentioned ROP Geometry Output SOP
or you can also use Geometry ROP

both of them have Transform parameter that you can set to Into World Space

Could you please explain in detail? i donnot get why you are talking about ROPs (Render Context)? I want simply export geometry from a SOP Context. When you are in a SOP context you can export with the file node. But then the tranform of the object level is ignored for objs. I am not sure we are talking about the same thing ;-)

Here are some sample pics. I think this makes it clearer.

here's a torus example

obj works as per @tamte's instructions but you'll note that in Max, the pivot is still at Origin, you'll have to:
- affect pivot only
- centre to object
- Reset Xform
- collapse