Creating shadow/shading patterns/profiles for trees in a 2D drawing

[Anonymous]

I create tree constraints plans for planning permission applications and have been asked by a client to now "update your drawing to show shading patterns" for the 188 trees and hedges on site.

I haven't a clue how to go about this. I've been googling for ages and can't find any useful information and would like to know if there is a simple method of creating a shape of the trees' shadow path for the day using AutoCAD LT, or if there is some add-on software that would be able to produce the patterns that I could then import into AutoCAD.

The information I have on the trees is their height, crown reach for N,E,S & W, stem diameter, and the centre point (or centre line for hedges).

My knowledge of AutoCAD is limited to the tree work I do (in other words, not very extensive), so it would be greatly appreciated if any information provided could be dumbed down.

Thanks!

[WarrenGeissler]

So you don't think everyone is ignoring you - the plain answer is no. In order to do shadow studies you need a 3D component (full AutoCAD - not LT) and if you want to try an add-on, unfortunately they will also not work with LT (the limitations are NO 3D and NO API extensibility)

[Anonymous]

Thanks for getting back to me!

I had a feeling that might be the case, but thank you for confirming.

I've opted for a basic arc of shadow reach between 9am and 3pm on midsummers day using suncalc.org to get the area's altitude angle of the sun for particular times of the day and the equation: 

Shadow Length =             Height of Tree                     

                              tangent(altitude angle of sun)

I plot the distances from the edge of the canopy spread for 9am and 3pm, and create an arc between the two points.

It's not a particularly accurate measurement of the shadows, but most of the information on Tree Constraint plans is more estimate than accuracy anyway, and it seems that this is roughly the approach taken by arborist software such as Pear Technology.

ArborShadow software provides a more accurate 2D shadow trace, but it seems quite difficult to navigate and I'm not sure if the information is transferrable to AutoCAD LT, so I feel I would potentially be spending more time figuring it out than it would take to produce the simple arcs.

Sorry to have potentially bored you with this information, but hopefully it might help someone else in the future.

Thanks again!