Given Houdini's procedural nature, when setting up a modeling scenario where one views the cage of a subdivided model and also sees the shaded version of the subdivided geometry at the same time, what controls the final rendered output of this geometry? Does one need to advance the “depth” slider at render time to get a completely smooth looking rendered model, or could one leave the subdivided surface at a relatively low depth, (2), and change some Mantra setting, or is the apparent smoothness at render time controlled by the subdivision “depth” set in the SOP, itself?

Greg Smith

Hi Greg,

There are two ways to render subdivision surfaces. One as you already know is to use the Subdivide SOP & the “Depth” value determines the smoothness.

The other way is to set the Object to render “Polygons as Subdivision Surfaces”. The option is found under the “Render” tab of the object in the Geometry menu. One caveat of this method is the “Crease” attribute will not be picked up when rendering. Also, for this method, you should set the Render Flag to the SOP before the Subdivide SOP, if you used it to visualize the subdivision while you model.

I hope the above helps!


Cheers!
steven

Thank you Steven for the reply. So, If creases are not an issue, would setting the “render polygons as subdivision surfaces” be the method to use if one needed to maintain near realtime previews of an animation? Would this method tax the system less than having a “subdivision/cage” setup in use as you animate? How would you do it?

Also, even though I have set up my camera to render 640 x 480 in its preferences, when I middle click the render button at the bottom of the viewer and select “Mantra1” it renders in a much smaller window. What must I change to always get a 640 x 480 preview?

Thanks again,

Greg Smith

Hey Greg,

Please note “Polygons as Subdivision Surfaces” is computed only during render time so you still need to have a cage/subdivision setup while animating. I haven't really animated with subdivision surfaces but a couple of suggestions:

a. Use a Depth value of 1 for better interactivity.

b. Lock the cage geometry & animate with that. You should get a good level of interactivity since Houdini does not have to compute a lot of SOPs.

c. Instead of playing back your animation, render the viewport to a flipbook & preview your animation. To do this, RMB on the Viewport Render button then select “View: Flipbook”. (Houdini 6.1 only)

With regards to rendering, are you selecting “mantra1” or “View: Mantra”? “mantra1” should render at the resolution of the camera selected in the mantra1 ROP. “View: Mantra” starts a render with certain default settings, one being a resolution of 320x243 which might explain why your renders are small. Also, you might want to check the mantra1 ROP does not have “Override Default Res” checked.

I hope the above helps!

Cheers!
steven

Another way Mike Cronin came up with was to bring up another viewer and used the render state to constantly do automatic re-renderings. This method is especially good if you have 2 cpus. I hope he doesn't mind me linking to his image.

Could you explain, possibly, step-by-step, how to set up Mike Cronin's render pane? I'm programatically impaired, so if you could lay it out visually, I would be greatly appreciative.

Greg Smith

Greg,

Split one of your panes from the pane menu or hit Alt+]. Set the new pane to no linking. set it to the obj level (or sop level). set the pane to be a viewer from the Network menu. In the viewer, hit tab->generic->render. Draw a selection box in your viewing pane and it will render that area. while you are working, it should update the render in the box (if it doesn't, hit the re-render button)

hth,
dave

Dave:

Thanks, it works, except, for the life of me, I can't find the “re-render” button. Does such a thing really exist? I can get the view to update if I do a view transform like tumble or zoom, but can't find that button.

Greg

Hey Greg,

If you look at the screen capture, you'll notice the “Re-Render” button at the top of the lower right viewport. It is most likely stowed in your desktop setup so move your mouse slowly over the top of the viewport until a long thin bar highlights then click on the bar to un-stow it.

Have you gone through the tutorial videos from both SESI & 3dbuzz? If you haven't, I highly recommend you go through the introduction videos which cover most of the interface as well.

Cheers!
steven