Final Lighting & Rendering

Third step would be to balance and tweak everything we have made so far. This is the most delicate stage and here we can start adding that fine details that our scene needs to have in order to look realistic.

Our main task is to avoid overexposure OR under-exposure (too dark shadows) and give proper contrast to the scene, that way our interior will get depth – And that is one of the prime goals of successful Arch. Viz. - avoid flat image/lighting.

For example, you got big openings - one against each other, and the lights might cancel each other appearance, by producing too much light from each side, and by doing that eliminating shadows.

In real world that's not really happening, there always will be one side that is darker than the other – as there will be always one source of light that will be stronger than another.

Sun is always directional (one direction) AND stronger than the artificial light, unless it's a very cloudy day and your artificial lights can provide much stronger lighting and dominate the scene.

So think about this like that, one source always needs to lead, and rest of the lights are just following!

Choose one source of light, natural / artificial – make it primary source for illuminating the scene, and add gradually, rest of the lights.

Pretty simple? Right?

That's another very important point – to add your lights gradually, one-by-one. Turn on/off other lights to test how that particular light works in your scene.

Lights we add:1. First light is ambiance (we learned how to add HDRI lights from the

previous chapter) make sure that this light is not overexposing. If it does, then turn down the Overall mult in the texture.

2. If you having issues with too strong shadows, but you like the ambiance overall, you can split the maps and use one for the Environment (as it is - very sharp reflections) and second map you can blur in Photoshop and use in VRayDome Light – the more blurry the image - the softer shadows will get. (You can control the strength of light for both of those maps in the Overall mult).

3. You can add VRaySun if needed and lower multiplier to match the scene.

4. Only after setting up the natural lighting, you can start adding artificial lights – and tweak each light separately and independently from other lights.

5. Do not turn artificial light “on”, that being positioned close to the window. If you have strong natural sunlight coming into the room, it will cancel your artificial lights – and you will not really see them.

6. If you can't get rid of overexposure, switch your color mapping to be Exponential – this color mapping method known for dealing with overexposure. You might get a bit washed out (lack of contrast) results, but it's much better than having overexposed image.

Beginners mistakes, usually will be, to use Linear (default) color mapping, and to throw several lights to the scene, click render and try to figure out what's going on...avoid that!

Add each light gradually, that way you will know how strong it is. As I mentioned earlier this is very delicate and the most crucial part of making Photo-realistic 3D Renders, and it's always easy to add contrast than to remove it!

So use Exponential and avoid exposure failures.

Flag & DeflectorUse Deflectors / “Flag”s to block lighting. If you have done all the previous steps, and you still get “some areas” overexposed (and it's very important to notice that I use the word some areas – that's not more than 20% of your image. If you get overexposure in over 20% of your image, you need to change your camera settings ISO OR Light Settings) – In cases like that, you can use cinematic approach and “flag” your sun.

You can use plane with holes, to let some light through but block most of it – the bigger the holes the more light goes through.

OR you can use just simple plane object, but remember to make it NOT VISIBLE to camera if it get's in your frame and it should not receive any shadows as well.

You can also use natural objects to “flag” the light, such as trees, palms..etc.

The final step will be to add artificial lights to mimic the reference lighting. You can use very low intensity lights, between 1-10 multiplier, and that should simulate the secondary bounces from the main light source.

Let's just recap that stage in one sentence: Fix the overexposure by using proper color mapping and HDRI intensity, block lights if needed, add additional lights with low intensity to simulate secondary bounces.

White BalanceWhite balance is a photographers technique to match the temperature of environment to the photo camera – that way you will get naturally looking colors.

Why it's called “white balance”, because we use white plate to measure room ambiance temperature by taking a probe of color from the white plate.

I'm going to use in my example a simple sphere, with default VRayMtl – which is mid gray; 128,128, 128.

The probe, that will be taken is not final, and it needs to be adjusted (make it lighter, because we use gray plate).

Why we use gray and not white?

Because white color get's easily overexposed, while gray can give us a good indication about color temperature of interior space.

12pm / Noon – will produce bluish colors, the room will get a lot of blue color from the window, the reason is that the SUN is very high, and it bounces lot's of blue color from the sky = 5600K (kelvin). The lower sun gets, the warmer color will become, and we might experience, orange/red sunsets.

White balance also can be achieved in Photoshop by using color balance tab, however the “source renders” are also very important. You will get much better representation of natural colors and materials if you set white balance in VRayPhysCam.

Here's an example of white balance renders; with & without. The probe of color was taken from the same spot.

As you can see, colors with white balance look much more natural and balanced towards white. In compare to the image that got NO white balance - all the image tend to have slight bluish colorization everywhere.

Of course, “Final Color Correction” and adjustments have to be done in Photoshop, since this is the only program that can represent colors in professional way, and set ICC profiles for printing OR web upload.

The best way to practice would be, to apply white balance to every render, this way you'll calibrate your “eye” to “see” correct “white color”. Basically, if you have rendered image from 3Ds max, try to balance the walls to be as white as possible by adding color balance in Photoshop the next way;

1. Midtones – a bit Yellow & Red2. Highlights – a bit Blue & Cyan3. Shadows – a bit more Blue / Green

If you get over-saturated colors from your objects, you can always use HUE / Saturation and select the color channel that you want to remove.Rememebr, color in white balance is the opposite color you are removing!

Final RenderThe time has come to finalize our render. So far we were using low quality settings to move quickly towards the end goal, by getting fast feedback, fixing the imperfections and moving forward.

There is few ways to optimize scene and prepare it for final render. One way is to configure the BEST Image sampler & Global DMC settings, and optimize the lights/shadows, GI and material subdivisions. This method works good for VFX and Film, however when you're dealing Arch. Visualization, and you move things around, change design, add models and lighting so frequently, you might not want to tweak your DMC sampler each time.

So what I suggest for quick navigation between the Low & High Res Rendering setups, is to save the presets and load them each time you want to switch.There are only few things I change to go from Low to High Res;

1. Adaptive DMC = 1,162. AA filter = VRaySinc3. Noise Threshold = 0.0054. Global Subdivs Mult. = 2.0 / 3.0 (double / triple the entire scene quality)

- Light Cache subdivs will be at least the width of the image.- Irradiance Map will be good for 2500 pixels and up.- Brute force will be good for 1500 pixels renders – will give grainy but realistic result.

Now it's time to activate the Render Elements and Press RENDER!