Hi there! I'm building a pergola in my backyard and I'm designing it in houdini first to get the plans.

I would like to accurately simulate sunlight and it's shadows according to my real life location and time of day.

Is there any way to do that within houdini?

Thanks a lot!

If you have a source(which are around) to bring in the data, yes. From what I've seen it's easy enough to get the suns' location for a specific time of day and location. But I suspect to do what you want your going to have to (unless you can find an app that generates it for you) is make a list from your source of datapoints and do some interpolation; Bringing in that initial data with python perhaps.


Here is one though that looks like you have all you need in terms of calculation:

http://www.pvresources.com/en/siteanalysis/siteanalysis.php [www.pvresources.com]

you can also use Sky Light

tamte
you can also use Sky Light

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That will probably do it! Thanks!

Tried the skylight…you can't use true lattitude though. Normally lattitude is given starting from the equator, but this light uses lattitude coming from north pole. So you will have to do a conversion. Also longtitude is not taken in east or west. Seems positive values up to 180 are west while negative values are east.(haven't tested a east value, but west values work).

SideFX main office is in Toronto sitting at approximately a lattitude of 43.6 deg.

To get that proper value in the camera parameter you have to subtract that from 90 and use the negative value, in this case -46.4

I guess one would have to script with python to change the months menu item and date to get a full year round animation.

BabaJ
I guess one would have to script with python to change the months menu item and date to get a full year round animation.

you can use Day Of The Year slider, it's float
I mean I have no idea how accurate this is

you can use Day Of The Year slider, it's float
I mean I have no idea how accurate this is

Yeah, that's a good idea. Will have to test that out.

For time of day it seems a bit off by 10 minutes. Also with the parameter for fractional day set to zero gives a ‘high noon’ result.

So looking at the soltices positions one day before and after seems to make day of the year at 1(the parm starts at zero) being January 1 starting with sun at Nadir.

So I forgot to consider differences between apparent and mean time. So for the one date I checked this shaved off about 3 minutes to make the difference that was expected of 7 minutes instead of 10.