Different results between DIva GH and Diva inside Rhino (diva2.0)

I did a simple test of an annual radiation map metric, with a surface orientated towards the south using a weather data (Montreal in this case). I did the test within GH and also inside Rhino (no GH) and I get different results. Although visually it looks the same:

The results I get form GH are :

Lower radiation : 1230 KKhw/m2*year

Upper radiation : 1289 Khw/m2*year

While inside Rhino the results are:

Lower radiation : 240 KKhw/m2*year

Upper radiation : 259 Khw/m2*year

I do not understand the difference between the two simulations, they should give the same radiation amount.

What I'm not doing right

Attachments:

Untitled.3dm, 1.4 MB
CAN_PQ_Montreal.Jean.Brebeuf.716278_CWEC.zip, 224 KB

Replies to This Discussion

Permalink Reply by Jeff Niemasz on April 23, 2012 at 2:24pm

Hi Claudio, the results you got for Rhino are definitely off. I checked the nodes file that your file is generating and it looks like the analysis direction is 0 1 0 for all of them so they are facing north, not south. It is good to offset the analysis nodes for the radiation map off of the surface a bit (because the meshing of a nurbs surface might "cover" nodes indiscriminately, not a problem if you mesh it yourself). Also, you can then see the direction of the analysis nodes then, if they offset the wrong direction then flip the surface and rerun the nodes until they come off the surface in the intended direction. In grasshopper, a method that is useful is to find the surface normal at the closest point on the analysis surface and use that as the analysis direction.

Attached are screen shots of what I got running a single south facing node in montreal in grasshopper and your model with the analysis direction turned around to face south (0 -1 0).

Hope this helps.

Jeff

Permalink Reply by Claudio on April 24, 2012 at 8:32am

Thank you Jeff for your time and effort. Yeah!!!! my mistake I consciously get this kind of error I will establish a method of always checking the Srf normals. BTW I Know the previous version od DIVA had problems with files seating on a server. I've tested many ways and came with the conclusion that any files to be simulated with Diva should be on my C drive or desktop. IS this the same for DIVA 2.0?

thank you

cheers

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