Render Tips 2: Exterior Lighting It is critical to understand the balance of variables of the Heliodon light source to achieve natural looking perspectives for exterior scenes. The right combination of Heliodon intensity, radiosity contribution and sky illumination guarantee a very impressive perspective. On the enclosed file called Exterior.atl there are 4 Heliodon sources used. Each Heliodon has a different mixture that combines sun intensity, radiosity contribution and sky illumination. The first heliodon --Heliodon 1-- which has only light intensity with no contribution of radiosity and with the radiosity engine turned off, gives the following render result: As you can see, the perspective is very dull, the contrast between well-lit areas and shadows seems very sharp and unnatural. To reduce this effect, we can apply the following: for the first camera view we activate the camera ambient light, which does not behave like a light source but gives a homogeneous brightness effect to the whole perspective (this is very useful in providing more clarity on scenes that otherwise would be too dark). It is recommended however to use this technique on low-light scenes since it gives an artificial brightness that can be undesirable on the result. The second view with Heliodon 2 has radiosity contribution applied with no sky illumination and thus the overall light distribution is already much better, but still not satisfying.