This page provides a step-by-step guide to using the V-Ray Physical Camera.
In this tutorial we are going to take a closer look at the V-Ray Physical Camera and the Lens Effects that are available with V-Ray. We are using the headphone scene from the previous tutorials.
To follow this tutorial, you will need to have the V-Ray for Modo plugin installed. This tutorial is a companion to go along with the QuickStart video posted on our YouTube channel.
To download the files used in this tutorial, click on the button below.
1) Add the V-Ray Physical Camera Package
To add a V-Ray Physical Camera to an existing scene in Modo, select the render camera in the Item List, and then go to V-Ray > Add Package > Add V-Ray Physical Camera to selected cameras.
This will add the V-Ray Physical Camera tab to the camera’s properties.
The V-Ray Physical Camera Package has a number of improvements to the normal V-Ray Camera and stock Modo camera which can be found under the V-Ray Physical Camera tab.
2) Adjust the exposure
Do a test render.
You will find that the render is very dark. By default, Modo uses the White Level value in the Final Color Output to determine exposure, whereas by default V-Ray uses the photographic values of F-Stop, Shutter Speed, and ISO, so there is likely to be a mismatch in exposure.
In order to match the luminance of the Modo camera, we need to increase the exposure by an estimate of four stops ("half" or "doubling" the value of light in photographic terms). We don’t want to alter the F-Stop value (aperture) as this determines the DOF and shouldn’t change from its current value. This means either the shutter speed or the ISO needs to be altered. In this case, we are going to alter both by adding two stops of exposure to each: increase ISO from 200 to 800, and reduce Shutter Speed from 200 to 50. While we're at it, turn on the Enable DOF option.
Do another test render. This time the render should match the original in terms of exposure.
Now that the exposure is fixed, we can use the Physical Camera tools to make some photographic adjustments to the image.
Begin by adding some vignetting and performing a test render. With Vignetting set to a value of 1.0, the effect will be subtle but still add a photographic lens feel to the image.
4) White Balance
We can adjust the White Balance by clicking in the color field next to the parameter to open the Color Picker palette. Change the Color Model from HSV to Kelvin in order to use the correct photographic values for adjusting the White Balance.
In photography, the purpose of white balance is to correct the coloring of light sources to make them more neutral (closer to white). This example scene uses mixed lighting, with two different lights which have very different color temperatures: one is a warm tungsten, the other a cool daylight. This means it will not be possible to white balance both the lights, so only one can be properly white balanced. In a scene with mixed lighting such as this one, the best approach is to find a pleasing balance between warm and cool that works well for the particular scene.
To Illustrate, we'll turn on RT and change the values of the white balance. In the Kelvin Color Picker window, when you drag the slider to the left the warmer light will become more neutral, but the cooler light will become even more blue.
When you drag the slider to the right the opposite will happen. The cooler light will become more neutral and the warmer light will become more orange.
We'll bring the slider a bit to the right to to neutralize some the cool light and emphasize the warm lighting. Do a production render.
4) Add some Lens Effects Glare
Now that we have a final production render, we can apply some post-processing Glare inside the V-Ray Frame Buffer.
Open the Lens Effects panel by clicking on the small Star icon at the bottom right of the V-Ray Frame Buffer.
To activate the effect, enable the On option for either the Bloom Effect or Glare Effect. For now, enable the Bloom Effect.
For this image, bloom may be too intense of an effect. Even if you decrease the Size slider, the image is softened too much.
Turn off the Bloom Effect and activate the Glare Effect by enabling its On option. The glare tends to only effect the strongest light sources and leave the sharpness of the rest of the image intact.
Use a high Weight and a low Size to add a subtle glare around the brightest highlights in the image.