Image Based Lighting

One of the cool things about creating art using a computer is that you have unlimited choice to alter, adapt and update a composition of an image that you are working on. When I’m working on art for a game, I often like to render the scene out to get a better view on my progress. Maya is very good at rendering scenes using its default lighting. But what if that’s not enough? Well we could create some lights of our own, maybe the 3 point light setup. That could be time consuming, and I just want to have a decent render for checking purposes.

Maya allows us to take advantage of a technique called image based lighting

Image based lighting is a rendering technique that takes advantage of High Dynamic Range images or HDRi for short. Most modern cameras and Smart Phones can now take these, which presents some interesting options for us. You can use your own panoramic HDR images taken with your smartphone, to create a dynamic background and lighting tool. Here is an example of how you can make a simple model look spectacular using HDR images for lighting.

A model of my dream car that I made, a Ford GTO.

Ford GTO in wire frame screenshot. Not a very interesting scene. Default lighting.

To render using Maya’s tools I select the render icon from the top menu.

Here is a render which is very dull. We need to apply textures to at least make it interesting.

 

Textures applied, looking better, but we can do more. Lighting is default and not really showing of the details in the car. Now for the magic. Lets setup Maya to use one of my HDR images.

Step 1.

Select the render settings button from the top menu of Maya

Step 2.

When the render settings menu appears, change the settings so the render being used is (1). mental ray, the tab selected is (2) Indirect lighting. Proceed to click (3)‘create’ on image based lighting.  Maya will prompt you to browse to where your HDRi images are located.  These are pictures you have previously taken to use as a background scene.

Clicking Create will open the attributes menu where you can adjust the parameters to the HDRi settings. You will also notice that a sphere has been created around your object and it will have the HDRi applied to it. Your viewport scene will look similar to the image below.

Step 3.

Select the render settings button from the top menu of Maya, e.g.

Switch (4) Global Illumination off and (5) switch Final Gathering on.

Step 5.

Select the (1)Features tab. Switch the primary render to (2)Raytracing. Select the tick box of (3) Raytracing. (4) Select the tick box of (4) Final Gathering

 

Step 6.

Click the render scene button to see the results of your HDRi settings in the render window.

Rendering takes some time as it is very processor intensive. Patience is required here.

Rendered with default lighting and no lighting adjustments. It looks good but has no shadows. Car is also very dark.

 

Rendered without default lighting and no adjustments. Cool, we now have shadows but the car is still dark.
We need to get more lighting out of the HDR image to really make the car pop out of the scene.

Step 7.

Go to the indirect lighting tab in render settings, select the black arrow next to reference name of the HDR image.

 

This will take you to HDR image attributes settings.

If you click on ‘Color Gain’ you can alter the amount of lighting in your scene.
I push mine up to 2.5 and that really makes the scene come to life. When you are happy with the value, do another render.

There you go a nicely illuminated car, using HDR images to create not only a pleasing background, but also to generate the lighting on the model.

One Awesome Ford GTO in a nicely lit scene.

That’s all for now. For more how-to tutorials. Send me an email or come visit me on floor two of 88 East Pender.


Roger Mitchell teaches 3D Modeling at VFS Game Design