Hello and welcome to the third and final instalment of this tutorial! The final objective is to create a bucket full of potatoes on dry muddy soil. In this instalment, we are going to cover lighting, rendering, and a little bit of postwork.

I usually write in British English. So that is what I have used here. Hopefully it will pose no trouble for American readers.

Step 01

We will not need HDRI lighting for a scene this simple. But we can still turn gamma correction on. If the final render is taken in 32bit full float, this step can be safely skipped. To turn gamma correction on, go to CUSTOMIZE > PREFERENCES and under Gamma and LUT, check Turn on Gamma/LUT Correction. Affect Color Selector and Affect Material Editor both should be checked. For bitmaps, input and output gamma both should be 2.2. The master gamma gives best results between 1.8 and 2.2. It depends on the type of image.

Step 02

Press M to bring up the Material Editor. With the material editor selected, press O to bring up its options. Since we have chosen to affect the material
editor, the background of the materials in the material editor will look washed out. If you feel uneasy about it, cut down both Back Light Multiplier and Background Intensity by half.

Step 03

There should be two light sources in the scene. The primary source is the sun. The secondary source is the bounced sunlight reflected by the ground. For sunlight, we will use the MentalRay PhysicalSun. If
the defaults (CUSTOMIZE > CUSTOM UI AND DEFAULTS SWITCHER) are already set to Max.mentalray, PhysicalSun and Sky will be activated automatically as we create a Daylight. Press the Daylight button, drag anywhere on the viewport to make a compass. Drag
again to create the sun.

Step 04

Select the sun dome and press 1 to bring up its options. Change the Position to Manual. Now it is possible to just move the sun until you are satisfied with the direction.
It is bright daylight we want to simulate, so we need not change the Multiplier, raising Softness a little bit does help though. Late morning or early afternoon sky normally looks blue. With that in mind, we will give the Red/Blue Tint a bit of positive value. Unlike most other parameters, Red/Blue Tint goes from -1 to 1. 0 is neutral, -1 is pure red, and 1 is pure blue. So, here we will get a nearly saturated 30% blue. Haze determines whether the sky is clear or overcast. Adding some haze preserves the natural colours of the textures better.

Step 05

Press 8 to bring up Environment/Effects dialog. When you create the Daylight system, Max will ask if you want to add exposure control. If you chose yes, the Active checkbox will already be checked. If you did not, now you can check it. The mia_exposure_photographic is easiest to configure in Max. But it always involves a bit of trial and error.

Since this is daytime and out in the open, light is abundant. We can use ISO 80 and Aperture f/8, which are standard for most point and shoot digital cameras in broad daylight. Since we want to set an overall warm-ish mood to the shot,
let’s change Whitepoint to 5400 Kelvin.

The idea is, 6200 Kelvin is more or less neutral. The lower you go, the warmer (more red) it gets. The higher you go, the cooler (more blue) it gets. The temperature of the sun is about 5778 Kelvin, which is almost white, with slight orange bias. The temperature of a candle flame is somewhere around 1500 Kelvin, which is bright saturated orange.

It is a common misconception that Highlights should be 1.0, Midtones 0.5 and Shadows 0.0, assuming it is a single scale varying from 0 to 1. Midtones is always 1.0 since we want full contribution of the actual colours. The higher Highlights go, the brighter the highlights. The higher Shadows go, the darker the shadows. There are no ideal settings for these. But if you leave them to 0, the render looks pretty washed out. So they both should have low positive values.

The Unitless 80,000 is a very significant value. For almost all outdoor situations, with or without HDRI, this value works just perfect. What I usually do is, set this value first and then tweak everything else. I have seen people work with 1500 Unitless. Doing that will cut off all weak light contributions, including weak secondary diffuse bounces and HDRI contribution.

So, when everything else is set, we can play with the shutter speed. In a real world camera, shutter speed for a bright sunny day could easily go up to 1/1200. But here going above 1/125 is underexposing the render.

Step 06

The next thing is to add a weak diffused fill light. For that, create a Portal Light directionally opposite to the sun. It should be at the ground level and not too close to the bucket. Shadows should be on. In the test renders below, I have disabled displacement for faster renders.

Step 07

The two things that most drastically affect rendering speed are raytracing and displacement. So we will choose the settings that offer decent but fast renders. These settings, by default, are at the bottom region of the Renderer
tab (when MentalRay is the default renderer).

Step 08

In perspective view, get the desired view, and hit Ctrl + C to create a Target Camera from that view. Hit F10 to bring up the render options dialog and under Common tab, set the desired resolution and pixel aspect. Finally, play with the Lens (focal length) and FoV (field of view) parameters to get the desired look. Right click on the camera name in the viewport and turn on Show Safe Frame and Lock Render to this View. Show Safe Frame will show you exactly how much is going to be rendered and Lock Render to this View will always render from that camera regardless which viewport is selected.

If you hit the render button right now, you will get a finished render. All you have to do then is to add DoF. Since I have used a Blend material in this scene, if we break things up in passes and put them back
together, the composite will never be 100% identical to the beauty pass render. I will explain why eventually. I intentionally chose to use Blend material with one Arch&Design and one Blinn so that we can see what happens when we are forced to use Blend but we cannot use the passes dedicated for Arch&Design aka mia_material.

So, if you are not interested in multipass rendering, skip to Step 10 and then to Step 15.

Step 09

Now let’s set up the render passes. Under render settings (F10), the Render Elements tab is dedicated just for render passes.

Let’s add the most basic passes: Diffuse, Lighting,
Shadow, Specular and ZDepth. Among these, specular and shadow have no options. Diffuse has only one option: Lighting. We will uncheck it to remove any shading information from the diffuse pass, so that we can later composite the same. For direct and indirect lighting passes, make two lighting passes. Both lighting passes will have the same three options:
Direct Light On, Indirect Light On, and Shadows. Direct Light on and Shadows will be checked and Indirect Light On will be unchecked for the direct lighting pass. It will be exactly the opposite for the indirect lighting pass.

One important thing to note here is, the Direct and the Indirect element both will have the same filename by default. So if you do not
manually rename them, the second lighting pass will overwrite the first without warning.

Since we have our image tone mapped already, there is no need of rendering out HDR images. When rendering LDR images, I would always recommend using PNG. It is lossless, small in size, widely
supported, and it can store Alpha channel.

Step 10

The Z Depth pass has 2 main options: Z Min and Z Max. These are nothing but the distances from camera in between which the Z Depth should be calculated. To optimize this, let’s look at the camera properties.

Turn on Clip Manually and set the planes such that they just safely contain all geometry in between. Now feed these values to Z Min and Z Max. If you check the Update box, the manually set clipping plane values will be fed to Z Min and Z Max every time you re-open then scene.

Step 11

If you render right at this point, you will probably get a diffuse pass that looks like this:

The mud material has taken over and the potato skin texture is barely visible. If you are seeing this, you have probably used a JPEG with Pyramidal Filtering (which is default) as the mask in the Blend material. The legacy diffuse pass deteriorates the quality of the mask terribly and as a result, one of the materials takes over. To partially solve this, get the highest quality image you can think of, 32bit EXR. Open the JPEG in Photoshop, change mode to 32bit and save as EXR. Now, in Max, use this EXR as the mask with gamma value overriden to 1 and Filtering set to None.

Now, if you re-render, the diffuse pass will look like this:

Even here the coverage of the materials are not identical to that in the beauty pass. But since this bug in Max has remained unsolved till date, this is the best result you are going to get. So a perfect reconstruction is not possible in this case, but we can still make it look good.

Above are the passes rendered with the new mask.

Step 12

Grab the passes, and drop them in Fusion. Get rid of the merge nodes that get automatically created.

If you were using Photoshop, probably you would be add all lighting passes in Screen mode. Though very common, it is a bad practise. Screen mode actually clamps the gains of both images being merged. As a result, the image often ends
up washed out and details are not so crisp. Instead, here in Fusion, we will just ‘Add’ the two passes. It is very easy.

1. Take a MERGE node (Mrg
   in the hot-bar above), plug the Diffuse to the background (yellow input) and
   direct lighting pass to the foreground (light green input).
2. Click on the MERGE node to view its settings and bring
   Alpha Gain all the way down to
   0.
3. Now view the result of the merge operation (drag the MERGE node onto the
   viewport).

For people following this in Photoshop,
this is Linear Dodge (Add) blend operation.

In 30% Additive (30% layer fill in Photoshop), it
will start to make sense.

Step 13

Merge another copy of direct lighting pass, this time in Multiply mode. We will turn the gain down a bit so that the shadows do not look so harsh.

Add the indirect lighting pass exactly like you added the first direct lighting pass, in 30% Additive. This will not do a great deal, except adding a very light tint and some brightness to the scene.

Step 14

For the specular, no settings need be changed. The image, along with its alpha channel, will just be over the composite.

At this point, if the shadows look a bit washed out, add the shadow pass in Multiply mode with a low Blend.

The transition from sunlight to shadow in a daylight scenario should not be this harsh on a rounded surface. This is primarily being caused by the direct lighting pass that we added in multiply mode. So we need to blur it. To fix this:

1. Drag a Blur node (Blur
   in hot-bar) onto the connection between direct lighting pass the merge node.
2. Set the Blur Size and
   Blend as high as possible. So the whole scene will be totally
   blurred.
3. With the blur node selected, click on the Polyline
   Mask (Ply in hot-bar) and create a
   selection just like you do with Polygonal Lasso Tool in Photoshop.
4. As soon as the mask it closed, the blur will be contained within it.
5. Click on the mask to access its settings and give
   Soft Edge a fairly high value, like 0.1.

Now, the only thing left to do is the depth of field.

Step 15

1. Take a Channel Boolean node (Bol
   in the above hot-bar) and plug the Z Depth pass to its background input.
2. Under the Channel Boolean settings, browse to the
   Aux Channels tab and set Z Buffer to
   Luminance BG.
3. Right click on the empty space of the flow view and choose (ADD
   TOOL > DEEP PIXEL >
   DEPTH BLUR) to get a Depth Blur node.
4. Plug the composite to the background and the Channel Boolean to the
   foreground of the Depth Blur node.
5. Under the Depth Blur node settings, choose Z as the Blur Channel.
6. Tweak the settings till you are satisfied.

Z Scale is the DoF transition softness. The higher the Z Scale, the softer smoother is the transition from focused to blurred.

The Depth of Field
parameter is, in fact, the range of the shot. Low DoF means all objects are close to the camera. High DoF means you can see quite a bit far in the image.

Focal Point, of course, determines where the objects in focus are. Large negative value means the object in focus is far and the near objects are blurred. As you slowly keep raising the Focal
Point, the blur will keep shifting away from the camera as focal length gets shorter.

Step 17

Put a Saver node (SV
on hot-bar) at the end of the flow, set end frame count to 0 (so that there is only 1 frame in the comp) and hit render.

Above you can see the final flow. I have added Color
Correction (CC in hot-bar) nodes in several places and blurred the shadow pass a bit to get the final result I like. It is purely a matter of personal preference. The comp gives us the render below:

And that brings us to the end of The Bucket tutorial series. I hope you have enjoyed it. I have tried to make it as comprehensive as possible. For comments and questions, feel free to write to me at shushens@gmail.com. Special thanks to CGCookie and Wes Burke to make this
tutorial available to you all.

See you in the next tutorial!