Solar response problem

Hi all,

I'll try to explain my problem from the general to the specific.

I'm attempting to show a how a topography changes in relation to the sun - probably moving toward showing the best places to farm based on solar angle (this is for a class workshop - not a literal interpretation).

I have created a mesh and from that a divided surface where I've found the center points of each.

I would like to relate the faces of this mesh (not the center points themselves) to the vector between the center points and the sun. This could perhaps begin to get at growing-degree hours along a topography as the sun passes over.

My main issue is that - after finding the vectors between the center points of the faces and the sun point (using the nGai sun) - i have just that: only vectors. I would like to tie these vectors back to their points on the faces and then tie the faces to a color or an extrusion based on the vector. For example - when the vector is between X & Y radians, the origin face is extruded a certain distance or changes to a certain color. As the sun moves, the vectors for each point on the ground will change and hence, a geometry will change b/c of that vector.

I hope i'm making sense here - i think the inherent problem is that after getting vectors between each ground point and the sun, I don't know how to tie them back to each point they come from and how to start to manipulate geometries based on that.

Any help or examples would be much appreciated. I have attached the definitions below.

Thanks,

Tom

Attachments:

topo_v3.ghx.3dm, 41 KB
topo_v3[autosave][autosave].gh, 270 KB

Replies to This Discussion

Permalink Reply by Benjamin Golder on October 26, 2010 at 10:46pm

Attached are pictures to show a simple example of how you can separate subsurfaces of a polysurface based on their orientation.

basically you just need to define the range of orientations that you want to select as "good". Here I've done this using sliders, and choosing x,y, and z ranges that the normal must fall within.

In terms of relating this to solar energy and growing things, you could either look at the amount of radiation or hours of sunlight. In either case, these would be calculated over time, not for a specific moment. So it wouldn't make much sense to calculate the amount of sunlight for one hour on one day out of the year. You would probably want to calculate the amount of sunlight over one season or one year, and then display a daily average. Measuring the amount of sunlight on a surface is often called "insolation". This will be directly correlated with orientation on an open terrain that is free of obstructions (shadows are a whole other consideration).

To relate this back to making decisions based on solar radiation, you then need to decide what is the range of orientations or quantities of sunlight that is "good enough". This would be a binary decision: either the surface has enough or not. Or you could rate the surfaces based on how much they have, so that some surfaces would have a high rating or a low rating. But again, you don't need to make a bunch of measurements to solar positions throughout any given day. You can just look at the orientation of the surface normals and directly correlate that with average levels of sunlight. You may also want to look at suitability analysis and Ian McHarg's Design with Nature (which was a foundational work in using suitability analysis for design and planning.)

This book is a pretty good primer on solar energy use and architecture.

Attachments:

Screen 2010-10-26 21.25.11.jpg, 31 KB
Screen 2010-10-26 21.23.15.jpg, 102 KB

Permalink Reply by Tom Gibbons on October 27, 2010 at 8:25pm

Great Benjamin,
I appreciate it - I've continued working with this definition - may try to combine things whereby using your suggestions to pull out faces that are "good enough" in regard to sunlight over a longer term as well as seeing surface responses through the day as the sun moves overhead.

Will post again if I run into any more serious roadblocks.

Thanks!
Tom

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