Setting up a scene with HDRI Lighting

prophet000

在外面看到的一个初级教程，对新手认识HDR很有帮助
新手可以看下，高手略过。。。


Setting up a scene with HDRI Lighting
In this tutorial we will run through the basics of setting up a scene with HDRI lighting.
Using HDRI lighting has its pros and cons. If you use it, you can archive stunningly realistic renders, without having to set up a complex lighting rig. However, it can cause very long rendering times.
Note: This tutorial is only for people with the Advanced Render Plug-in that comes with most editions of Cinema 4D.
Get an High Dynamic Range Image
The first  step in setting up HDRI lighting is to find an High Dynamic Range Image. These are NOT Images rendered WITH HDRI (as SOME people may think…). They are their own format. You will find these images with a “*.hdr” extension.
You can find many very high quality and resolution probes here. A Probe is just a type of HDRI which encompasses a large view.
If you lay the probe flat and looked at it, it would look like this :

This will be the Probe I will be using for this tutorial.
Now, as you can see by looking at it, it has odd black stuff around the edges, and if we stuck that as out lighting now, it would be uneven, and unrealistic. Luckily Cinema 4D has a solution for that.

With that being said, open up Cinema 4D. When it loads, go to Plug-in > Advanced Render > Convert HDR Probe. It will open a file box. Navigate to your hdr file and open it.
This will convert all of the verities on the picture, to that of a 3D sphere. When it’s done it will pop up with the finished image. You can simply close that. If you look in the directory that the .hdr file was in, you will now see a con.hdr file as well. That is the file we will be using to light our scene.
Setting up the Scene
if you have a premade scene, feel free to use that. If not, then simply create a Floor object, drag it down 100m on the Y-axis, then create a Sphere.
Create a new material, named it ball, leave the colour as white, and change the brightness to 100%. Uncheck Specular, and check Reflection. Change the reflection brightness to 6%.
Duplicate the Ball texture, and name the second one Floor. On the floor texture, check the Bump, and add a Noise texture. Change the Noise type to FBM, and the Octaves to 6.1. click on Bump again, and change the strength to -7 %.
Now add the Ball material to the Sphere, and the floor to the floor. Now our very basic scene is done, and if done  right should look something like this:

Setting up the Lighting

On to the fun part. Start off by creating a sphere. Then resize it so that all of you scene fits inside it (for the example scene, giving this sphere a Radius of about 1200m should work fine).
Now duplicate that sphere (Ctrl+c, Ctrl+v). Name one sphere GI, and the Other one Visible. As the names suggest, one of the spheres will be visible when we render and the other one will be for GI (GI stands for Global Illumination).
Create the materials needed for the light
Create a new Material. Name it Visible. Turn off all of the channels except Luminance. After that, go to luminance, and apply your con.hdr as the texture. As you can see, it’s a bit bright, so we are going to tone it down a bit. We can do this by setting the Brightness to 0%, and set the Mix to 50%. Then it should look like this:

Now duplicate this material, and name the duplicate GI. The only change we are going to make to this one is setting the MIP Blur Offset in the Luminance Channel, to 10%. By doing this, it evens out the light, so when its rendered it will not look as blotchy.

Now, apply the GI material to the GI sphere, and the Visible material to the Visible Sphere.
Setting up the spheres
Now we will have to change some settings for our spheres. So right click on the Visible Sphere in the Object browser, and go to Cinema 4D tags > Compositing. Click on the tag. Make sure only the following are checked:
Seen by Camera, Seen by Rays, Seen by Transparency and finally Seen by Reflection.
Once that’s done, also add a Compositing tag to the GI sphere, and make sure only the “Seen by GI” is checked.
Now, after all of that complicated work, your Object Browser should look like this. (if not then you messed up). Our scene is finished now, now we only need to set the correct rendering settings.

Rendering

If you tried to render it now, well it would look like a normal every day render. But that’s not what we want, we are going for Photorealism. So for that we are going to need some Global Illumination.
Open up the Render Settings, and go to the Global Illumination tab (Note: On the older versions of Cinema 4D it was called Radiosity) and turn it on. Now, you could spend a half hour messing with the settings, tweaking them to get them just right… OR you could use these:

Once that’s all sorted out, click on Options, and make sure you turn off Auto Light. If you don’t, your scene will looked all messed up.

And now for the usual end stuff. Click on Antaliasing, and change it to Best. Click on Output, and change the Size to 800×600. Go to Save, and pick a path to a safe place, and change the format to JPEG.
This is my final result:

To sums things up here is a quick reference guid you can use in the feature:

• Create 2 spheres (Visible and GI) that go around your whole scene
• Create a new material, turn off everything except luminance and add your HDRI image.
• Apply this material to your 2 spheres
• Visible Sphere > Compositing: Seen by Camera/ Rays/ Transparency & Reflection
• GI Sphere > Compositing: Seen by GI
• Render settings: Turn on Global Illumination and turn off Auto lighting

教程下载在这里 Setting up a scene with HDRI Lighting.rar (151.16 KB, 下载次数: 29)

2009-3-27 14:36 上传

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tsang1

感謝分享！

xuyanfirst

效果看到很不错，研究下

wymangum

yun....全英文？

ideaer

我是初级看不懂啊啊啊