I apologize for the lack of an update last week, I took the week off due to a family illness. So no work done means no update either!
This week I’ve been working on validation of the ray tracing model. I though I’d found another forward ray tracing code that I could use to at least validate mine, solstice, but in the end I’m not sure it’s worth it. Kudos to the developers of solstice at making it easy to install, see my post on how to do that, but massaging the output data into a form I can use takes a long time. Then making sure my scene objects are setup correctly and comparing with my ray tracer… not sure that it’s worth it. I also tried soltrace and it kept crashing so I gave up on trying to validate with that too.
What I did do was go back and carefully redo all the internal rayctracer tests (my ray tracer is called rayctracer because it traces rays and is written in c++. It is not racy but maybe that helps remember it’s name). Once these were good, I made a box in CAD and 3D printed it.
I made a diffuse light source with some 100% diffusing greenhouse plastic and some LED strips that sits perfectly on top of this box. By exporting the files to .stl, I can run a simulation of the rays in that box and also measure the real light flux in the box with PAR sensors. I feel like this is the only way I’ll really be able to trust that my rayctracer code is accurate enough.
There are a bunch of complications to doing this in real life. First, the PAR sensor isn’t perfect and grazing angle rays aren’t picked up as well. I’ll have to correct for that in the simulation. Second, the albedo of the inside of the box is unknown. I painted it black so I know it’s low, but that will have be be a fitting parameter. This actual test will be next week’s task.
The growth chamber tomatoes continue to grow despite my watering problems. Leaf angle continues to be oriented towards the south wall and the southmost plants have less leaf area than others, which makes sense they don’t need it. They also seem to have larger fruits, but I’ll have to wait until harvesting to measure that.
Sun Aquasystems 