Modeling Roman curtains: Rendering over window - Part 3

29 Mar, 2015 gus_ann (3dsmax vray expert)

Hello everybody!

As a final touch, I decided to write a final lesson in the series "Roman Curtain".

From the lesson you will learn:
How to implement a global substitution of material in the scene, as well as how to selectively exclude scene objects from this spoof.
How to adjust the color of a bitmap texture using the ColorCorrection parameter map.
How to create a composite Blend fabric material for curtains based on VrayBlendMtl.
How to use the two-way VRay2SidedMtl mat and how to influence the power of the GI material VRayMtlWrapper.
How to automatically detect overexposures in a scene using VRayFrameBuffer - Force color Clamping.
How to use the Parametric Output map.
How do the typical settings for the VRaySun and VRaySky ligament for the interior look?
And of course in this tutor we will dwell on some of the problems that arise in the process of creating an interior, relating to the overshoot of the curtains themselves, as well as window slopes.

The re-illuminated zones are a fairly common phenomenon that almost every visualizer encountered. I will show several techniques that help to avoid such moments.

The first thing I would like to pay special attention to is setting the Burn Value of the Color Mapping rollout. As we know from the lessons of RenderStuff, the recommended value of this parameter in the universal settings of Vray is 0.35. That is, it is recommended to put this value in any type of visualization, be it an interior, an exterior or a subject visa. But there is a small subtlety. Often it is in the interior visa that there are problems of over-exposure - strong daylight hits the window, gradually reduces its intensity and is distributed around the room, which manifests itself in different degrees of illumination. At the window there is a terrible overexposure, and the distant parts of the room can not be illuminated enough.
Parameter Burn Value - (literal translation - the value of burning), plays a huge role in the formation of overexposures.
I'll show you a simple example in which all the settings for the scene will be exactly the same except for the Burn Value:

From the above pictures it is clear that Burn Value burns light zones. Therefore, I came to the conclusion (experimentally) that when visualizing an interior, this value should be, in some cases, not higher than 0.2, but better than 0.1.

I apply this method to the scene I have already created.
To begin with, I set the visualization settings. My settings are immediately final:

I will adjust the materials gradually, one by one, so I visualized in the gray material of VRayMtl to estimate the overall illumination of the scene:

Then I deleted the windows (in my window there are four) from the OverrideMtl ​​list in Global switches:

The lighting settings in the scene are very simple. I put VRaySun and VRaySky, made him a bunch:

Excluded curtains from the OverrideMtl ​​list in the Global switches:

30 Mar, 2015 gus_ann (3dsmax vray expert)
30 Mar, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3

For curtains, I decided to make a complex mixed material. The main fabric will be beige, with a blue - green pattern. The Vray BlendMtl will help me to accomplish this.
I'll select an empty ball in the material editor and assign it VRayBlendMtl:

In the Base slot I'll put VRayMtl:

I'll go into it:

In the Diffuse slot I'll put the texture:

The main material on the idea should be beige, so I'll apply the ColorCorrection card to this texture. To do this, I click on the Bitmap button and select ColorCorrection from the drop-down list:

On the question of the program, whether to dump an old card or leave, I will say - "Leave":

The ColorCorrection window opens, in which I change the Hue Shift (shade) and I will display the texture by changing the Gamma / Contrast value:

I will go to the sublevel above:

In the slot Reflect I assign the map Falloff:

We go into the Falloff map (it will open automatically), go to the Output item and turn on the checkbox Enable Color Map:

Then I will be able to edit the Falloff curve. Edit mode leave Mono (that is, black and white), and, by adding points and adjusting their knobs, shape the curve:

Note that the lower boundary of the curve is near the very zero, just a little above it.

Let's exit the Falloff map settings:

And we will remove a tick of reflections Fresnel reflections, Reflect Glossiness we will put equal 0,4:

We'll go into the Maps parameters of this material, and in the Bump roll we'll put a black and white analog of Diffuse card:

Then the Bitmap map window of the Bump slot opens.
Set it to Blur for the texture of 0.01:

The manifestation strength of Bump is set to 10:

Now give a little texture of the transparency of the fabric. Copy the map from the Bump slot, put it in the Opacity slot. We put the power of transparency 10:



30 Mar, 2015 gus_ann (3dsmax vray expert)
30 Mar, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3

Go to Blend material.
Copy the created Base material and paste it into Coat slot in copy mode. We will name this material Uzor:

Now it turns out that both Base and Uzor materials are exactly the same. Let's fix this by removing from Diffuse the ColorCorrection card in the material Uzor, leaving only a clean blue map:

Remove the card from the Opacity slot in Maps:

Now we have a complex material consisting of two others (Base and Uzor).
The first - beige with transparency, the second - blue, opaque. They are now mixed fifty-fifty percent equally with each other. I want to draw a picture on the curtain. So I go to the Blend material and put a black and white ornamental map in the Blend Amount slot (blending map):

The resulting Blend material will be assigned to the main fabric of the curtains, previously calling it Osnovnaya Tkan:

It's time for the first test render:

Since the curtain geometry is not thick (it is essentially a one-way plane), then we need a two-sided material on it. Click on the VrayBlendMtl button and select the VRay2SidedMtl from the list:

In the settings of VRay2SidedMtl I will increase the value of Translucency:

On the test render, we see obvious light on the main material of the curtain:

Well, let's leave it as it is and make the material sidewall.
To do this, copy the Base material and paste it into an empty slot:

In the diffuse slot, remove the ColorCorrection card and leave the blue texture.
Click on the VRayMtl button and change the material to Vray2Sided:

Assign this material to the sewing of the curtains.

At this stage it can be seen that the fringing looks normal, but the main fabric is over-exposed.

Let's go to the VRay2SidedMtl main fabric. What do we see here? This is a two-sided material, the first slot of the Front is laid VRayBlendMtl (beige fabric with a blue pattern). The second slot Back material does not put anything:

This means that on a one-sided plane, which is essentially a curtain, it has no thickness, two materials are superimposed - the first Front, the second - Back material. The Front material is on the side of the room. Back material from the street side. If nothing is put in the Back material slot and a check in front of it is not worth it, it means that the same material is used on both sides of the curtains, which lies in the Front slot. In order to get rid of overexposure, I need to cheat a little and copy the material from the Front slot to the Back material slot in the copy mode:

30 Mar, 2015 gus_ann (3dsmax vray expert)
30 Mar, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3

Now you have to be very careful!
I'll go into the VRayBlendMtl material in the Front slot:

Click on VRayBlendMtl and select VRayMtlWrapper from the list:

It will look like this:

What have we done? We now want to change the properties of the Front material, which looks face to the room, with the help of VRayMtlWrappper.

Raise the reception of secondary global light rays with the material of the curtains from the side of the room, setting the value of Receive GI = 2, thereby increasing its illumination by "secondary":

Let's go to the sublevel up to VRay2SidedMtl:

And now go to the Back material:

Click on the VRayBlendMtl button and also assign VRayMtlWrappper to it:

Now we will reduce the reception of secondary global illumination rays, overexposed by the curtain material from the side of the window (more precisely, from the side, the bright glowing VRaySky sky behind it), setting the value of Receive GI = 0.4 and thereby reducing its illumination to compensate for the overshoot:


Peresvet left.

I, perhaps, will make the beige curtain material more transparent by increasing the Opacity parameter in the Maps rollout for it to 25. (I'll have to do this by finding it in the Front and Back material of the VRay2Sided material):

Let's look at the slopes. They are overexposed, even taking into account that it is gray standard material 128.

If they are assigned a white color, they will generally burn out, their light range will simply go beyond the perceived range for the eye. Like this:

If you are not well-versed in the problems of overexposure, and you find it difficult to identify overexposed zones, then a button in VRayFrameBuffer called Force color Clamping (the output power of the color range) will come to the rescue:

In the below render, Force color clamping is turned on, and this function very clearly shows the overexposed zones (in the example of one window):

We will work with them.
But first you need to remember the course of physics and answer the question, what about the properties of white and black. For these properties corresponds to the so-called "Albedo" substance.
If we explain in the simplest and most accessible language, judging from Albedo, pure white has 100% light reflections, medium gray 50%, absolutely black does not reflect anything, so we can not see it (black hole in space). According to the course of physics, any white material has its own meaning of albedo, that is, the power of reflection. And this is the power of reflection can never be 100%. In fact, there is no such substance in nature that would reflect 100% and would be absolutely white. Just as white does not seem to you, you can always find a substance with an even more white color 🙂

So, the concept of white - this concept is very, very stretchable.

30 Mar, 2015 gus_ann (3dsmax vray expert)
30 Mar, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3

I'll add the slope and wall geometry to the exception list (the Exclude ... button near the OverrideMtl) in Global Switches.

In order to reduce the light on the slopes, I need to lower the "albedo" of white color for them. To do this, I'll go into the material of the slopes, click on the button of the Diffuse card and from the offered list I assign the Output card:

The Output map settings window opens, I click on the None button and I insert the VRayColor card in the Output map:

I will assign the color VRayColor:

I will go to the sublevel above to the Output map and set the RGB Level value to 0.35:

Let's look at the renderer that turned out (on the example of one window opening):

Apparently, the overexposure on the slopes has left.

We will deal with the material of long curtains.

I will exclude only one curtain from the OverrideMtl ​​influence in Global Switches and I will customize the material on it.

So, create a simple VRay material, call Portiera and assign it to the curtain:

In Diffuse put a map Composite:

I will increase the number of sub-materials in Composite to three:

In the third slot of the sub-material I'll put the texture:

I'll go into the settings of her card, set the Blur 0.01 blur option, press the Bitmap button and assign a ColorCorrection color correction card over this card:

In the ColorCorrection card setting, set the brightness value to 14:

Copy the ColorCorrection card. Let's go to the sublevel above and put it in the second slot in Instance mode. And in the first sub-material in the copy mode:

In the first sub-material, we remove the brightness correction:

Let's go to the sublevel above to the three layers. We need to mix them through the Falloff map:

Falloff map settings for mixing the third and second layers:


To mix the second and third:



Let's make a small Reflect material:

Put the Bump map into the material:

Click on the VRayMtl button and change the material to VRay2SidedMtl:


That's it. I will remove the gray VRayMtl material from the OverrideMtl ​​list altogether and render the entire scene:





30 Mar, 2015 gus_ann (3dsmax vray expert)
30 Mar, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3

Friends, I would like to note that you should not blindly follow the lesson, repeating all my actions, "one-to-one."

This lesson is based only on my own observations and my own practical experience to deal with overexposed areas in the window openings interior 3d visualizations. Do not hesitate to take it as a basis for their own experiments.

I hope that my experience of this material is useful to you!

Creating roman blinds - Marvelous Designer. Lesson from gus_ann. Part 1

Creating roman blinds - retopologiyu. Lesson from Usco and gus_ann. Part 2

Creating roman blinds - Visualization in the window opening. Lesson from gus_ann. Part 3

31 Mar, 2015 Ilya
31 Mar, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
Anya, I want to express my gratitude and thanks to you in particular, as well as children from Usco RenderStuff, for the Mega-work !!!

30 Mar, 2015 gus_ann (3dsmax vray expert)
31 Mar, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
Ilya, hello. 😉 Thank you. We have tried to as much as we could and as far as the appearance of free time. Usco helped me. Model bivalve painted wooden windows, as well as all the textures of fabrics - his work. So from me and he thanks a lot. But, to be honest, with the "Mega-hard" you are greatly exaggerated😁. I hope the lesson is useful.

4 Apr, 2015 Maksim
4 Apr, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
What a strange geometry of windows, thanks for the lesson learned so many new, always struggled with overexposure to the eaves through VrayOverrideMtl.

30 Mar, 2015 gus_ann (3dsmax vray expert)
4 Apr, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
And what exactly is in the geometry of the window raised doubts?

4 Apr, 2015 Maksim
4 Apr, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
Model good but the outside is what the illusion of a mirror but we all know that it is double-wing

30 Mar, 2015 gus_ann (3dsmax vray expert)
4 Apr, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
Well, I knew about what is meant by the mirror illusion ..... In general, the window was not done in one day, and it worked to the maximum. Everything is done on the basis of's reference and more. Perhaps there are more of my mistakes as a visualizer than just errors in the geometry of a model in its proportions. If you read the whole of it there was the claim or question (do not even know what to call it), we will assume that the lesson was a success, that the main theme of the lesson (which is not exactly "the geometry of the window"😉 has reached the reader in full. 🙄

31 Mar, 2015 Ilya
4 Apr, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
Anya, if the box is playing such an important role in the scene, you can put the scene too? Or is it impossible?

30 Mar, 2015 gus_ann (3dsmax vray expert)
4 Apr, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
Ilya, a window on the contrary played a minor role. It can be anything in your scene - single leaf or double plastic frame - has a fundamental value which one. The scene can not put as it is filled with models is not my own production and the right to free dissemination and no one gave me.

31 Mar, 2015 Ilya
4 Apr, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
I mean empty stage, without models that you can not publish. Not a problem, since you can not, then you can not.

4 Apr, 2015 Maksim
5 Apr, 2015 # Re: Modeling Roman curtains: Rendering over window - Part 3
Lesson super, super result forward to the fourth lesson about the post-processing 👍

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