Hi,

I am learning Houdini and after working on this test scene for a while, I now have a few Houdini questions for you experts

(Here is the test animation (Flipbook) - Please note that I'm new to character animation, this is my 1st, and I will re-do it later and render with shadows etc.

http://sundstedt.se/blog/?p=2988 [sundstedt.se]

1) Why are there incorrect “pops” in the flipbook render as you can see if you play it (character disappears)?

The issues are not there when going through the animation frame by frame in Houdini or when FlipBook is “rendering” out the frames…. (from what I could tell). Not very nice.

2) In my Tree View, I have so many objects (like tracker data etc.), is there any way of “grouping items in the Tree View so that I can have them in a folder so that the Tree can be better organized so less scrolling is required? I can't find any in the manual.

3) My character is standing on a polygon plane that is my reference for the table surface, I need to see this surface (line) in my Right (Ortho) view for example when I am animating to make sure feet is on the ground, but there are two problems. a) The plane is not showing when it's not selected (in the Tree View, and b) to actually see the plane in ortho views, view needs to be set to wireframe or Hidden Line Visible, is this normal? (is it because height of plane is 0?). I need to see my plane when character is selected!

4) When working in the Channel Editor, having keyd everything on the Character, I may for example have animated everything using ‘Constant’ for my Function, when I now want to select everything in the Channel Editor (All keys in the timeline) on the graphs, I have only found one option which is to ”rectangle select“ all the curves/keys in the Channel Editor, the problem is, the computer grinds to a halt and it takes like a minute or longer until the selection is ”computed" and the drawing of the selecting rectangle is so slow that I can't be sure all will be selected. I want to convert a large set of keys to for example bezier….. Is there a better way? Why is it so slow? (900+ frames on Toon Character, Everything Keyed but I don't think it's more than about 50 main poses and some further keys…

I will have more questions but I thought I'd try to throw these here as this is my first post in years

sundstedt
1) Why are there incorrect “pops” in the flipbook render as you can see if you play it (character disappears)?

I was getting incorrect lighing in my flipbooks with earlier builds of Houdini11. Please upgrade to the latest and see if you still get the odd frame with incorrect lighting.

I was getting a bug where the odd flipbook frame was getting incorrect lighting. I haven't seen this in the most recent builds of Houdini. Please install the latest build and try rendering the flipbook out again. If the problem persists, submit a bug.

sundstedt
2) In my Tree View, I have so many objects (like tracker data etc.), is there any way of "grouping items in the Tree View so that I can have them in a folder so that the Tree can be better organized so less scrolling is required? I can't find any in the manual.

There are several ways to organize your /obj scene directory.

First I like to use the Technical Desktop as a starting point. The Tree view on the left is good for navigating Houdini but as you are experiencing, if you don't collect operators in to physical SubNet objects, it can get unwieldy.

You can collect like operators in to Subnets and work that way. One subnet for lights, another for objects and so on if you wish.

You can view the nodes as a proper parenting tree view if you wish. I will create another pane tab beside the tree view and set it to a network view. I convert the network view to a list (t key shortcut) then using RBM, change the List Order option to “tree view”. Now you can inspect the network as a tree. There is a bug where the next time you go in to a separate network pane it may show up as a tree view so just hit t in those networks to toggle to network view.

You can use the network editor and collect nodes in to Network Boxes. You can stow/expand network boxes to manage workflow.

You can organize your nodes using groups or bundles.
First Groups. Groups are a collection of objects for a specific path in an network. In any network pane, hit the “x” key to open the group widget. You can select any number of objects and create a group for them. You can then control the various flags on those groups of objects.
Groups are homogenious in that they only support a specific operator type (obj, sop, cop, etc) and are limited to the current network path.

Bundles are similar to Groups but are global and can contain any node in Houdini in the same bundle. They are heterogenious.
You have to create a bundle new pane type. They work similar to groups in that you can drag-n-drop objects to create new bundles.
There is the ability to create smart bundles as well that can use prefix midfix and suffix masks along with operator type filters to automatically collect objects in to bundles for you. I work this way very frequently when organizing my scenes.

See the help for bundles and groups. If you do some searching you will find that there is some confusion between bundles and groups. I use groups mainly for organizing a complicated local network like a character rig or a very large SOP network where I know things are going to remain local to that network. I will use bundles for organizing scenes along with collapsing some objects in subnets for lighting and rendering.

I am sure others organize data differently as well.

It helps to have dual monitors to lay out your desktop with specific interfaces. For that it is best to decouple the various network and parameter panes by using the link buttons in the upper right of these pane types. That is the little pin icon in the upper right. Clicking it will either pin (lock) or unpin that pane to that network. It can do a lot more though. RMB (RightMouseButton) on the pin icon and you will see a list of options. Lots of power users will create a few parameter-network linked panes where they will link them together by choosing the same number in the link pin. For example, you can create a 3wide x 2high pane desktop where parameters are at the top and networks at the bottom then change the link pins together for each pair of parm-network panes. 1-1, 2-2, 3-3. One could be for objects, another for SOPs and a third say for Outputs or whatever.

When you do work this way, you can have a nice association between objects and SOPs that at one time in Houdini's history was the way you worked and a lot of power users still choose to work this way today. If you have a pair of network/parameter panes together, you can link them all up to pin to 1. Then dive in to SOPs. Finally in the network/parameter pane pair that you wish to display objects, RMB on the pin and enable “Link as Parent”. Now when you navigate the Object network panes set to link as parent, the SOP network and pane will follow along.

No matter what, when you have a desktop configured to the way that you like, save it using the main menu Window > Desktop manager and set it as the default desktop. If you split off new panes on to other monitors, the desktop will save those split panes as well.

I have seen some amazing desktops and workflows in use over the years. I wonder if some of the old time power users would share snapshots of their various desktops spread across two or more monitors. You can read a lot in to how they work by how they organize their desktops.

sundstedt
3) My character is standing on a polygon plane that is my reference for the table surface, I need to see this surface (line) in my Right (Ortho) view for example when I am animating to make sure feet is on the ground, but there are two problems. a) The plane is not showing when it's not selected (in the Tree View, and b) to actually see the plane in ortho views, view needs to be set to wireframe or Hidden Line Visible, is this normal? (is it because height of plane is 0?). I need to see my plane when character is selected!

I'd give it a bit of thickness to have it better read in the ortho viewports. It's a known issue. I'd just put an Extrude Volume after your terrain grid and adjust the thickness so it reads better.

sundstedt
4) When working in the Channel Editor, having keyd everything on the Character, I may for example have animated everything using ‘Constant’ for my Function, when I now want to select everything in the Channel Editor (All keys in the timeline) on the graphs, I have only found one option which is to “rectangle select” all the curves/keys in the Channel Editor, the problem is, the computer grinds to a halt and it takes like a minute or longer until the selection is “computed” and the drawing of the selecting rectangle is so slow that I can't be sure all will be selected. I want to convert a large set of keys to for example bezier….. Is there a better way?

Yes there is. The Channel Editor has three modes: Graph, Table, Dope Sheet. The three icons in the upper left of the Channel Editor Pane.
Use the Table View. There are two options in the table view: Edit Values or Edit Functions available from the menu pull-down. Choose Edit Functions. Now you can quickly convert all constants to whatever segment function you want.
Follow this workflow as I do when I do blocking with constants and then move everything to beziers to work up the motion:
- Scope (select) the channels you want to modify the functions for.
- In the Channel Editor, change the edit mode to Table.
- Change the view mode to “Edit Functions” from the menu above the table.
- Shift-Select all the names on the left hand side. You will see all the table entries drawn in orange = selected.
- To the right of the menu currently set to “Edit Functions” is the menu to select the function to use for the selected orange fields. Choose “bezier”.
Done in an instant.

sundstedt
Why is it so slow? (900+ frames on Toon Character, Everything Keyed but I don't think it's more than about 50 main poses and some further keys…

This is a bug imho as it should be quite fast. Turning off the View option “Show Values for Selected Keys” doubles the redraw speed… Turning off the View option “Show Times for Selected Keys” gives you even more performance. Seems like the drawing of text is slow in the graph editor right now.


As an aside, have you started to use the channel groups? An easy way in to getting to use channel groups is this:
- RMB (RightMouseButton) on the toon rig top asset and choose the menu option:
“Create Nested Channel Groups”
and follow the prompt(s).
In the Channel pane, if you have channel groups on for display, you will now see every folder on the toon asset is it's own group of parameters. Selecting a channel group will scope all the channels in that group for you to edit.
You can pin that group to lock it down for blocking out keys if you wish and more.

Hope that helps.

I am really happy with your detailed and helpful explanations! I will be trying out the things you have told me and it's really helped me and will be helpful I think to others as well. Thanks again!

So is that a typical workflow with character animation, to do constant first and then bezier etc. ? I've just started with character animation and I'm starting to study some training course videos but of course they are all for Maya etc. as I don't think there is a whole series of character animation videos for Houdini?
(I've watched the one in old school blog).

Thx
Anders

sundstedt
So is that a typical workflow with animation, to do constant first and then bezier etc. ? I've just started with character animation and I'm starting to study some training course videos but of course they are all for Maya etc. as I don't think there is a whole series of character animation videos for Houdini?

I am what they call a survival animator but have been around quite a few brilliant animators. Animating in Houdini is really no different than other applications. Actually there's a good chance that what is a plug-in or script in another app is supported somewhere in Houdini's interface. Ask away as you animate more in Houdini.

There does seem to be two main camps when it comes to animators. Those that can do straight-up animation and those that do blocking and then refinement.
Straight up is where you plow the character through the shot posing the entire character as you move forward. By the time you reach the end, you are mostly done. I have only seen a handful of animators who can do this successfully and I swear they already have the character animated in their mind even before they put down the first key.

For the rest of us there is blocking and then refinement and the seemingly infinite variations on this. Many will block with constant values and pose the character at key positions through the shot and then to the in-betweens. Having said that, the flipbook has a neat feature where if you inherit the current character scope in the flipbook set up dialog, then you get the blocking in the flipbook for re-timing.

There are a ton of resources on character animation either as books or on-line. This is one area where instruction is very helpful and most schools do a decent job of teaching general animation. For me to say any more about animation would be doing a huge disservice to all real animators out there.

All of this is very helpful, thanks!