Noob Questions - RPC + Exposure

[loydg]

The problem with flexible software is that it can get overly complicated. I certainly appreciate a good preset when they are offered.

Linear and Automatic exposure controls are not supported by Mental Ray. I'd suggest the mr Photographic EC. Are you using Final Gather by chance?

Although Mental Ray doesn't have quick check setting like in Revit, there are ways to up the quality. Under the Renderer tab you can adjust the minimum and maximum Samples per Pixel. The default is 1/4 min and 4 max. I'd start with 1 and 16. Any higher and you'll have some wicked render times.

HDR rules! If you are into PhotoMatrix, check out some of the photos on this link:

http://www.pbviz.com/forum/Topic1897-81-1.aspx

Pretty cool stuff. We use HDR quite readily as a secondary lighting source and reflections, both in override through V-Ray. You can achieve a similar look using the MR sky system. It's simple to set up and and some basic controls and adapts to the more "dramatic" morning or evening lighting. Initial setup is easy:

1) Create>Systems(the gear thingies)>Daylight>Click-n-drag
2) Environment Panel>Environment Map>open mr Physical Sky

Then it's tweaking the setting to get the result you want. I like to set the position on the light to "Manual" so I have more control with my scene.

Keep the questions coming! That's what we are here for..

[Grumple]

Hi Loyd,

Thanks for all your guidance : )

But now you've asked for it...

Are you using Final Gather by chance?

What exaclty is Final Gather? I've seen it, but the phrase means nothing to me : |

Under the Renderer tab you can adjust the minimum and maximum Samples per Pixel. The default is 1/4 min and 4 max. I'd start with 1 and 16. Any higher and you'll have some wicked render times.

Ok... What the hell are samples? : | I've heard them mentioned and refered to many times, a google search proved fruitless... And why does it use a minimum and maximum of them?

We use HDR quite readily as a secondary lighting source and reflections, both in override through V-Ray. You can achieve a similar look using the MR sky system. It's simple to set up and and some basic controls and adapts to the more "dramatic" morning or evening lighting.

I spent about 2 hours reading about how you can use HDR for this yesterday. I have absolutelly no idea what they were going on about : | I read one tutorial with some guy that uses a chrome ball about 15cm diameter with one half painted grey - he takes a photo of it then takes another photo of it from the other side then takes photo's of the grey side - he then performs some kind of warlock spells and creates a 3d environment/image/I'venoidea : |

It was making sense at 1 point - but I now just don't understand what this is for at all! Why is this related to HDR imaging? What is this 'globe' image used for?

Keep the questions coming! That's what we are here for..

Man are you regretting that now!! : P

[stusic]

What exaclty is Final Gather? I've seen it, but the phrase means nothing to me : |



Ok... What the hell are samples? : | I've heard them mentioned and refered to many times, a google search proved fruitless... And why does it use a minimum and maximum of them?

I may sound like a jerk saying this (and I don't mean to), but... don't be afraid of the help files! 3ds has a very detailed and thorough help system that will at least give you an idea of what it's talking about -- and pertinent to 3ds, not another program as google results may return to you. Check out the sections on lighting. It's a lot to read, but it's a very important part of max and it's hard to learn through trial and error. Read up and, if you're still scratching your head, we can elaborate.

I spent about 2 hours reading about how you can use HDR for this yesterday. I have absolutelly no idea what they were going on about : |

HDR (High Dynamic Range) is pretty simple once you get the basic theory down. It's very easy if you're familiar with photography.

One of the fundamental problems with photography is correctly exposing a photo with dramatic range of highlights and shadows. Generally you have to pick whether you want to expose for the bright areas or the shadowy areas.

Using an example of a person standing in front of a bright blue sky, if you expose for the sky, the person will show up very dark, almost like a silouette. However, if you expose for the person, the beautiful blue sky is going to overexpose and be washed out. By taking a range of photographs with varying exposures (that expose correctly for the darker areas, the brighter areas, and a few in between, you can use a program like Photomatix (which is what I use) to blend those exposures into one photo that shows everything exposed correctly -- the person and the sky.

I haven't done any HDR with 3ds, but I have done quite a bit with a real camera:

http://photos.phillipbradshaw.com/p44814903

I read one tutorial with some guy that uses a chrome ball about 15cm diameter with one half painted grey - he takes a photo of it then takes another photo of it from the other side then takes photo's of the grey side - he then performs some kind of warlock spells and creates a 3d environment/image/I'venoidea : |

I have no idea either...

I hope this helps a bit!

[stusic]

You must spread some Reputation around before giving it to Steve_Bennett again.

I didn't even think of that...

[loydg]

No regrets. Questions like these always stretch me to learn Max better. After 10 years I still don't know the whole program inside and out. I only know enough to get me into trouble.

Some of the deeper stuff in Max is like asking why the wind blows. At some point I just give up and except that it works for whatever reason. But that's not necessarily helpful. Pierre Felix can chime in about mental ray any time!

Phillip is right about the help files. They've been a big help for me to understand what some of the options/buttons/gizmos actually do. However, the help files are fairly vague on why you should use things. Let me see if I can illuminate (pun intended).

Final Gather:
Sounds like something out of Highlander, but it's a process of global illumination in mental ray, and a way to crank up your render times. This is one of those options that can help or hinder your rendering. The default values are never quite right so there is always a tuning to get the desired results. Its basic principle is to smooth out global illumination. Awesome for still renderings, but can wreak havok with animations if certain polygon criteria are not met.

Global illumination:
I'm sure you've noticed that the shaded side of a building isn't black and is quite visable. That's due to the light from the sun (or other light sources) bounces around and ends up hitting that side. Also, as the sun's rays pass through the atmosphere, some are redirected and come in from all angles (sky dome light). Most advanced renderers (like mental ray and V-Ray) use a similar process with the lights or cameras. They project "rays" that will strike and bounce off of objects in the scene. The rays will loose intensity with each bounce depending on each object's material reflective properties (is this making sense or am I starting to sound like one of the help files?).

HDR (in Max)
We use HDR images in Max to simulate a lighting environment. The renderer will use the dynamic range of the image to cast its rays, so darker areas of the image will cast fewer rays while the bright white areas will cast more. In some cases a scene can be lit solely with an HDR image for a nice soft look. Most of my exterior scene use a single direct light source (sun) and an HDR image in the environment overide (V-Ray). The same image can be inserted into the environment map slot to make the background consistent with the lighting. Creating my own HDR images just isn't my thing. I try to avoid the painted balls and warlock spells myself and just purchase the HDRs from a good online source.

Samples:
This mental ray's filtering method and a way of controling the antialiasing of your renderings. The higher the samples, the cleaner the render (and the longer the render time). It has more to do with the pixels in the image than with the scene. When I use mental ray, I try to keep my sampling fairly low until it's time for the final.

Once you get a set of setting in MR that you like, I highly recommend saving them out as a preset from the render dialog box (at the bottom).

Here's a thought: would all you mental ray gurus out there be willing to post some of your typical settings for interior and exterior scenes? Really just the setting you find yourselves mostly tweaking. That would be a huge help for folks just getting into it.

[loydg]

Thanks Glen,

Anywhere that does decent FREE people I can use? : |

Not quite got the 2.5k for Rocketbox's library...

Cheers

I know that you could probably grab a few sample people from Rocketbox, AXYZ, and LowPolygon3D. Maybe it would be enough to populate your scene. We get some on the content CDs from 3D World that are decent. I'll have to see who they were from and I'll wager they have them on their sites.

Alternate option: get some people in your office to pose in the general locations of the rendering and cut-n-paste them in post with Photoshop.

[Grumple]

Okie Dokie... Hell of a lot of info there!!

It all just about made sense though, thanks very much : )

I tend to only hit F1 as a final option! I find that it either has what you're looking for then doesn't tell you how to do it, or explains things horribly (in Revit at least)...

I'm still a tad confused with the using HDR as a light source thing : | Is it literally a sphere with the image pasted over it then told to illuminate (like a paper lantern with a pattern on it?!)??? How does that light/create an environment? It would surely just create crazy shadows all over the place : |

Many thanks for all your input guys, I really want to learn this stuff - there just seems almost too much to learn...

Jay

[iamreavis]

I can highly recommend 'Realistic Architectural Visualization Using 3DS Max and Mental Ray' as an excellent guide to lighting, material, and scene setup in MR. I kept it next to my keyboard for a loooong time until I got comfortable with the Mental Ray controls. It's pretty easy to get nice-looking images from MR, but I prefer the visual style I get from V-Ray. More saturated colors, and the V-Ray proxies are nice for controlling scene size and hence display performance. I use V-Ray for walkthrough animations here at work, from 2-5 minutes long. I'm slowly adding Backburner render nodes as they're needed. Depending on the quality settings, I can render the whole animation (3000-5000) frames, in as little as 6-8 hours. You might also check out an Autodesk white paper, http://images.autodesk.com/adsk/file...hite_paper.pdf. I printed it out for reference and keep it on the bookshelf behind me.

[Grumple]

Thanks : )

I have looked at that book a couple of times, is it right for an absolute beginner though?
Does it come with pre-made scenes to work with, or does it expect you to have your own already?

[stusic]

Thanks : )

I have looked at that book a couple of times, is it right for an absolute beginner though?
Does it come with pre-made scenes to work with, or does it expect you to have your own already?

It contains all the project files it uses in the book. It's specifically for lighting and materials in mr, so it doesn't cover much (if any) modeling. However, I think if it's lighting and materials you're after, than this book would be good for anyone, as an introduction for a beginner or a refresher for advanced users.