How do I measure the dimensions between two specific points?

[adamkewley]

AK: question ported from LinkedIn. It has been edited to fit the discussions format.

I am using OpenSim Creator 0.5.1 for modeling. Doesn't it have a tool for giving dimensions between two specific points like any other CAD software?? I want this to define offset frames for joints. It's so time consuming to give them the coordinates x y z.

Specifically, I meant other than having to put absolute coordinates for a specific point (frame), isn't it easier to put relative coordinates with respect to a point that the coordinates are known? Like giving dimensions from one point to another. Finding every frame's absolute coordinate might be a little time consuming for complex models especially for robotic mechanisms where the location of joints and constraints must be accurate.

[adamkewley]

The coordinates in XYZ of an offset frame is essentially its "dimensions" w.r.t. the thing you're offsetting from. There's a ruler tool, but that usually gives approximate (it's based on geometry surfaces) euclidian distances between two points. Offset frame locations are always relative to the parent frame when editing an OpenSim model. This is how OpenSim is defined. OpenSim Creator's mesh importer hides this by putting everything into absolute coordinates (the intention being that people importing meshes probably don't have an OpenSim model topology yet).

Update since 0.5.1: OpenSim Creator now has better tooling for typing distances, positions, etc. relative to a user-selected frame in the property editor. With that tooling, you can:

• Select what you want to place (e.g. a marker, an offset frame)
• Go to the properties editor
• A dropdown menu above the position should be shown, and defaulted to (parent frame)
• You can then select a different frame in which to edit the quantity (note: this doesn't change the sockets, attachments, etc. of the component - it's purely UI tooling)
• After selecting the frame, you can then edit the quantity in the chosen frame