OTOY Forums

I have just had another go with the alembic grass feature, and am still struggling to control the result.

It seems like the y size parameter gets ignored when the grass is being generated (reducing it does not seem result in shorter grass being generated), and while rescaling it for already generated grass seems to do something, it also lifts the grass off the ground - so it seems to rescale scale from an origin somewhere above the top of grass rather than at the base.
(note for what it is worth, the proxy object used for the grass is sitting with its base level with the mesh, though I understood the proxy location should not matter either way, and that the origin of each grass object in the alembic file is whatever the surface of the mesh is at that location?)

Also struggling to change the material - whenever I select a new material and click 'ok', what looks like a small dialog flashes for a microsecond before disappearing - and nothing otherwise seems to change.

I am probably missing obvious things, but would be interested to know what they are.

Mate,

You definitely need scatter good model of grass if you want to have good result.

It seems like the y size parameter gets ignored when the grass is being generated (reducing it does not seem result in shorter grass being generated), and while rescaling it for already generated grass seems to do something, it also lifts the grass off the ground - so it seems to rescale scale from an origin somewhere above the top of grass rather than at the base.

May I suggest to debug this by saving the scene to ORBX and then opening it in Octane Standalone - where you can see exactly what is in the Placement nodes for the grass ABC file, and so determine if the problem is related to a Y axis scaling problem, or a Y axis translation problem. Also, make sure the proxy host Object is at Y coordinate 0 in the scene.

Paul

face_off wrote:

It seems like the y size parameter gets ignored when the grass is being generated (reducing it does not seem result in shorter grass being generated), and while rescaling it for already generated grass seems to do something, it also lifts the grass off the ground - so it seems to rescale scale from an origin somewhere above the top of grass rather than at the base.

May I suggest to debug this by saving the scene to ORBX and then opening it in Octane Standalone - where you can see exactly what is in the Placement nodes for the grass ABC file, and so determine if the problem is related to a Y axis scaling problem, or a Y axis translation problem. Also, make sure the proxy host Object is at Y coordinate 0 in the scene.

Paul

I don't know a lot about the standalone version (I use the ArchiCAD plugin to avoid using a separate platform) - but from what I can see there the behavior is the same. Sliding the scale float value results in same floating grass outcome. Also looking closely, once Y scale is reduced below 1 and the grass starts to float out of the ground, I can see half the grass points upwards, half points downwards.
The values for the 3D translation node all remain on zero. The host proxy object was placed at the origin (0,0,0) in ArchiCAD. I have attached the orbx file, for what that is worth.

Scottiefeng wrote:Mate,

You definitely need scatter good model of grass if you want to have good result.

Yes this has been what I typically would do, but seems a shame that the built in feature seems not to be working - it might otherwise be quite handy

I have looked into this some more. In summary, if you are using the Generate Grass function, leave the Scale sliders at 100%. If you need to adjust the height of the grass, re-generate it with a different Height setting.

Also struggling to change the material - whenever I select a new material and click 'ok', what looks like a small dialog flashes for a microsecond before disappearing - and nothing otherwise seems to change.

To adjust the material, click the grass proxy host, and the Octane material for the grass will be selected automatically in the Materials tab.

Paul

face_off wrote:I have looked into this some more. In summary, if you are using the Generate Grass function, leave the Scale sliders at 100%. If you need to adjust the height of the grass, re-generate it with a different Height setting.

Also struggling to change the material - whenever I select a new material and click 'ok', what looks like a small dialog flashes for a microsecond before disappearing - and nothing otherwise seems to change.

To adjust the material, click the grass proxy host, and the Octane material for the grass will be selected automatically in the Materials tab.

Paul

Hi Paul. The grass height setting doesn't seem do anything for me

The grass proxy host is invisible once grass is generated - I presume you mean that I need to select proxy in the ArchiCAD 3D window rather than in the view port as I normally would for everything else.

The grass height setting doesn't seem do anything for me

It seems to be working fine for me. What exact steps are you doing pls?

I presume you mean that I need to select proxy in the ArchiCAD 3D window rather than in the view port as I normally would for everything else.

Correct.

Paul

Hi, I am not sure what I can add that is not obvious re steps taken:

With the grass generation dialog open , if i enter a value that differs from the default grass height 0.1m (eg. when I change grass height value to 0.05m) nothing about the rendered result changes from the case where the default 0.1m height is accepted unchanged .
Maybe a rounding error that treats 0.05=0.1 ?
There is also still the issue of grass blades poking downwards instead of upwards from mesh surface half the time that requires twice as many blades as it should to make a lawn look ok

The grass height value is definitely working. Make sure you click the Reload button for the proxy are regenerating the .ABC file. And yes, there are some poke thru's below. This is a limitation of the grass scattering function.

Paul