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Hi all,

I did some tests with sun (set position and date/time). The rendered images
don't match reality. See image bellow



see the table. Sun rises at 5:27, so if I set time to 4th hour, I really can't get this result with visible shadows...

Where's the North? I mean at the upper side of the 'fence'. If so, the shadows from pipe don't match the table.

any idea?

um, your gmt is wrong. it should be gmt+2. daylight saving time starts on the 27th of march.

rivoli wrote:um, your gmt is wrong. it should be gmt+2. daylight saving time starts on the 27th of march.

you're right. I've to set SM to 2. but the result is still bad. Sun rise is 6:27, but the same image, rendered with SM=2 and 4 o'clock gives bright result.

Hi znouza,

What plugin are you using?

oscarMaxwell wrote:Hi znouza,

What plugin are you using?

Hi Oscar,

I'm using Rhinoll 0.5.1 and Maxwell 1.1.33

try to add 7.5 degrees to the longitude (see previous post).



this is a quick'ndirty render of an horizontal sundial. As you can see, to get the correct position of the shadow, I had to add 7.5° to the longitude.
Lightwave plugin.
HD

hdesbois wrote:try to add 7.5 degrees to the longitude (see previous post).

this is a quick'ndirty render of an horizontal sundial. As you can see, to get the correct position of the shadow, I had to add 7.5° to the longitude.
Lightwave plugin.
HD

I'd like to, but Rhinoll doesn't have (hope will have) the option to enter Lat/Lon directly (or add another city to the list).

sundial... hmm it's cool hdesbois,
maybe it'll be so cool if we have one for maxwell as an helper object

znouza wrote: but the same image, rendered with SM=2 and 4 o'clock gives bright result.

is the image only too bright or you still get direct sun shadows as in the first test?

rivoli wrote:

znouza wrote: but the same image, rendered with SM=2 and 4 o'clock gives bright result.

is the image only too bright or you still get direct sun shadows as in the first test?

at 4 o'clock I have to get dark (black) image no matter if GMT offset +1 or +2 ... the sun rises at 6:30... so any result than dark is bad. I got a little bit darker image than in the first test.

true, i was just wondering that if take a picture at 4 o'clock with a long exposure the resulting image may be bright as well. for this reason i asked you about shadows. i mean brightness may depend on your camera settings, shadows of course not.
maxwell does not have a physical night sky though, so i may be totally wrong.

I did another test with correct sundial created. Its desk is elevated of 48 degree (as is the latitude of Munich). Sun moves over sky of 15 deg every hour.

Maybe that' a plugin related issue. I ran a few more sundial tests, and except for the longitude problem, they are correct (Lightwave plugin, tests for 11th of March so as to limit the equation of time).
Not sure this will help, but I put a link to an horizontal sundial longitute-corrected for Munich. You only have to add equation of time to get legal hour (daylight saving time not accounted for). It's more easy to read.
the dial :

and the style at the same scale :

HD

Actually I don't think that it's a plugin related issue - or to be more exact: The issue may be in the plugin code, but the error is consistent for Cinemaxwell, too. i can't get it to macth the Cinema sun simulation, which gives good and expected results.

Watching at the sundials it seems that the sun is too fast around noon.

There's good code for this problem freely available that is exact to a few minutes, I don't understand why NL is sticking with a model for the sun position that seems to be wrong.

If they have problems with this, they should just post the source of the sun position routine and ask for help. I'm shure some of us would gladly get this straight. This is not rocket science anymore, but I do understand that they have different tasks to do and this might not be their top priority.

Kabe

This report is revisited and updated here:
http://www.maxwellrender.com/forum/viewtopic.php?t=4135