Sunday, August 07, 2011

[ Houdini Cookoff ] 02

Yes, finally I got my act together to acquire the plate, as well as capture the image sequences required for creating a hdri map.

First off is the location.
A nice window sill, with a nice cloudy sky providing beautiful soft shadow. It's a little tough to see, but there are four dots of blu-tack setup in a 12x12cm grid - this will be to ensure ease of camera matching the plate, and visible by the shooting camera at all times.The cup specifically chosen to be easy to model in Houdini (i.e. straight sides), and has its bottom blu-tacked to the sill so as not to move during the stirring action.
For the actual shoot though, I'd put a white box as a makeshift reflector in order to lessen the contrast of the shadow side of the cup.
In terms of image acquisition for the hdri map, I'd found a great recommendation by a colleague - Ball Finials in a chrome finish! A whole lot of these can be found at John Lewis (in the UK). The surface is far from perfect, but it is very solid, and more than adequate for little projects like these.

From the reflection above, I am actually quite close to the sphere; barely few feet away. Usually for HDRIs, you'd want to be far away so as to present less of the photographer in the ball, and being further away will better simulate an orthographic camera. Sadly, due to physical space constraints, I brought out my 200 and 300mm full sized SLR lenses but I simply could not find the space. I just hope these env maps will work! I only need them for reflection and diffuse lighting. Obligatory link to Paul Debevec's website on light probes.

Stills were acquired in two positions, from the shooting camera's POV, and one with the lens axis parallel to the ground. For each shooting position, I'd shot at iso 100, F2.8, 1/2000 to 1/4, giving me wide range of exposures to pick from. Each of these positions were shots twice, with different white balances (Cloudy and Custom) as I know my raw converter software does not do well with the white balance of the Lumix LX5.

Above is the plate :3 Well one of them anyways. Haven't yet decided which to use. I shot it overlength, and will only use at max 15 seconds, or less - I only have 4gb of ram on my home machine, and tests so far are already hitting the ceiling. Not really wanting to buy more ram as I rarely hit the ceiling.

The first few seconds was to allow the camera to settle down after I pressed the shutter, and the next few is to allow the milk carton/bottle to fill up the tea. Next, I stick the end of a spoon into the cup, stir, and pull out the spoon.

Originally, I'd thought to leave the spoon in, but I do not think I have the time to properly integrate a live action spoon, hence the stir and remove. I will probably need to create a stand in cg spoon element, and hopefully the motion blur seen in the plate above won't cause too much issues. I'd also blu-tacked the spoon at the 5cm mark to give me a frame of reference when I'm matching the animation. *Not* looking forward to that.

Well now that I've got plates and ldr images for the hdr map, no excuses....

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