Capturing the motion of trees

Turns out it's a pretty hard problem. But it does involve quality time outdoors in the wind playing with technology. This is a picture of our set up in a park in Orem, Utah. We've got a laptop next to a weather station in the grass. Some motion capture equipment on a wire running to the tree and a little wind speed measuring device next to the tree.

We made three important discoveries with this set up. First, debugging a technical process in 16 MPH wind is not that easy. Second, we should have brought a little camping table to put our stuff on. Third, our mocap system didn't save our data the way we thought it would save our data and we lost all of our data.

Other than that, it was a good trip.

Directability in weathering simulation

Directability is the ability of a director to exert control over a process which is used to generate an image or shape. Or, said more clearly, directability is artistic control. CG natural phenomena for use in CG film should be directable.

We added some directability to our weathering simulation by allowing the director to edit a curve (really a sequence of line segments) which specify the durability of the rock. The weathered rock takes on the profile of the durability curve.

The resulting process is a lot like the use of curves in specifying plant shapes as found in a paper by Prusinkiewicz called "The use of positional information in the modeling of plants" It's an interesting paper and their images are pretty amazing.

Cavernous weathering

Cavernous weathering is the process by which, well, caverns form in rock. These caverns are also called tafoni. We've been working on a cavernous weathering simulation and have some results. This is a fake canyon which includes some cavernous weathering. The rock shapes were created using our simulation and the image was textured and rendered in Vue. Implemented by Joe Butler.

Conquistadores Field Trip Report

On Friday November 2, a few of us went down to Little Holes Canyon near the San Rafael River to check out the Conquistadores as a field work test site for our upcoming modeling project. After a little "navigational ambiguity" on the rim of the canyon, we found our way over to the Conquistadores and determined that this is a near perfect test site for us.

We want some rocks which are visually complex, easy to get to but require traveling on foot and afford 360 degree access. We got all of that plus 360 degree access from above (on the canyon rim) and below (on the canyon floor).

The geometry is a little intimidating, but that's what makes it research. We thought it would be important to photograph some of the funkier shapes so that potential reviewers would know that the shapes were real and not an artifact of the modeling process.

Natural Phenomena in... "Surfs Up!"

I watched Sony's Surf's Up! the other day on the small screen. The use of natural phenomena was refreshingly ambitious most of the time and comically over-ambitious at others. Overall, it improved my impression of Sony's Animation group. A group of Sony Animation VPs and others came out to BYU for a visit a few weeks ago. They had good feedback for my student Cory Rheimschussel's cloud effects in "Kites" (mostly "that's hard, good luck") and the concept art for "Cloudy With a Chance of Meatballs", some of which was done by a BYU animation intern, looked great.

Back to "Surf's Up!"... it was good to see directors use weather, wind and time-of-day in a story. Scenes on the beach front, generally, included trees moving in the ocean breeze. A few scenes were actually set in weather other than sunny and clear. The rain was nicely done as was the sea fog. To my recollection, this is the first film in which trees moved in the wind and the weather was part of the set. Nice job.

Early on, there was a scene in which Cody rode a whale out of Shiverpool. Unfortunately the water-to-foam transition on the whale's wake was done poorly. Laughably poorly. I felt like I was watching a concept shot in dailies. I was surprised that it made the final cut. The transition seemed to be implemented as "when the curvature passes horizontal, switch immediately to foam!"

Possible Field Work Sites

We are looking for a field work test site somewhere in the desert. We need a place with the following characteristics:

1. Within 2.5 hours of Provo, Utah.
2. Includes a cool looking rock formation. Need to walk around the entire rock formation.
3. Low elevation. We want year-round access.
4. Is between 1 and 2 miles from the closest road. This is negotiable though.

Got any ideas?

We are thinking of using the Conquistadors near Little Holes Canyon near the Grand Canyon of the San Rafael Swell, see picture above. The problem with the Conquistadors is that they are next to a 50 foot cliff with loose rock. Safe enough, but safer would be better.

We are also thinking of using the first Pinnacle (following Steve Allen's guidebook) in Pinnacle Canyon off the Tidwell Draw North Road.

Reflectance from Photographs

Here's the problem: we've got an object of known geometry in a known location at a known time. The problem is to get the color and reflectance from a collection of those photographs. That's a large part of the intellectual merit of this proposal we are working on. The photograph shows such an object in my driveway on a Friday afternoon. The cylinder is 12 inches high and has a diameter of 6 inches. We painted it with matte and semi-gloss spray paint. The painted portions will allow us to calibrate our results with surfaces of known color and reflectance.