Sky

[Jan Davis]

How do I get a realistic sky?  I was good at the process in Accurender 4, but now the best I can get is a gradient between two colours.  How do i do clouds?

[Roy Hirshkowitz]

nXt does not have clouds-- at least not yet.  You may want to use photos, or HDRIs (trickier, but ultimately better) for your sky.  Some of our users may have suggestions.  www.accustudio.com has a pile of standard background images.  Good quality HDRIs can be found in the "Content and Entourage" section, under Download/Buy above.

[Jan Davis]

I will try that. Can you please describe the process, though?  From an earlier discussion, I understand that the image should be pasted as a decal onto a shape in the sky, but when I tried that last time, it blocked the sun!  

[Roy Hirshkowitz]

For non-HDRi backgrounds (standard photos) you have a few choices:

1. The background tab has a Use Image checkbox if you've selected Color and Image as your Visible background.
2. If you use WalkAbout, you can attach a background to your view using the Background Tab (you have more interactive control of size and positioning that way.)
3. My preferred method, although somewhat more advanced, is to render your drawing without a background, save it as a .png with Alpha, and use Photoshop or eq. to compositive the background and your rendering together.

[Marc Chaumier]

Yes, Roy, but with this method, you don't have the reflect of the sky in the windows. And with the sky as hdri, I find the setting of the sunlight more difficult... Often, I need the hdri, only for reflections, just to put some realism on my windows, but not for background. I have to play with the intensity cursor, and I find it not so easy.

Roy, can I put an hdri only in reflection, or do I have to put the same in refraction? Is it normal to put the intensity to far more than 100?

[Jorge Javier Lara Domínguez]

Marc, tal vez te pueda servir este truco para tus reflejos de las ventanas. Saludos. http://www.desarrollomultimedia.es/articulos/efecto-reflejo-gafas-c...

[Roy Hirshkowitz]

Marc Chaumier said:

...

Roy, can I put an hdri only in reflection, or do I have to put the same in refraction? Is it normal to put the intensity to far more than 100?

You can do whatever you want.  My preference is always for accuracy.  A single, well calibrated HDRi and physically correct glass material are always my preference-- and should result in accurate reflections.

There is no current standard for the units in HDRIs-- so yes, depending on the file you may need to scale it up or down quite a bit to make it play nicely with the sun or sky.

[Alfons Akamp]

Wird es denn irgendwann mal in nxt echte Wolken geben oder ist das garnicht geplant??

Alfons

[Roy Hirshkowitz]

No plans for clouds at the moment.

[Jan Davis]

I have found an HDRI image online o test with.  How do I insert it into the rendering?

[Marc Chaumier]

Thanks a lot, Jorge, for your help. I would like to avoid to use pshop as more as possible... I did sometimes reflections with pshop, but not exactly as shown in this tutorial. I will try next time. Thanks.

[Roy Hirshkowitz]

http://wiki.mcneel.com/accurender/nxt/documentation/beyond/hdri

There are some included with nXt as well.  Look in the folder where nXt resides-- usually Program Files/AccuRender nXt -- then /Support/HDR/.

[Jan Davis]

I have found five hdr files there - now how do I insert them into the drawing?  Is there any way to view them first? (The file names are, for example, campus_probe.hdr) Somehow, I think that is not a sky image.