Mixing displacement and multiple bump maps / November 1, 2017 by Xuan Prada

A very common situation when look-deving an asset is combining various displacement and bump maps. Having them in different texture maps gives you the possibility to play with them and making very fast changes without going back to Mari and Zbrush and waste a lot of time going back and forward until reaching the right look. You also want to keep busy your look-dev team, of course.

While ago I told you how to combine different displacement maps coming from different sources, today I want to show you how to combine multiple bump maps, with different scales and values. This is a very common situation in vfx, I would say every single asset has at least one displacement layer and one bump layer, but usually, you would have more than one. This is how you can combine multiple bump layers in Maya/Arnold.

The first thing I'm going to do is add a displacement layer. To make this post easy I'm using a single displacement layer. Refer back to the tutorial I mentioned previously on this post to mix more than one displacement layer.

Now connect your first bump map layer as usual. Connecting the red channel to the bump input of the shader.

in the hypershade create a file texture for your second bump layer. In this case a low frequency noise.
Create an avergage node and two multiply nodes.
Connect the red channel of the first bump layer to the input 1 of the multiply node. Control the intensity of this layer with the input 2 of the multiply node.
Repeat with previous step with the second bump layer.
Connect the outputs of both multiply nodes to the inputs 3D0 and 3D1 of the average node.
It is extremely important to leave the bump depth at 1 in order to make this work.

Iron Patriot wip 01 / July 7, 2017 by Xuan Prada

I'm working on a texturing and look-dev course for elephant vfx and this is the asset that I'm preparing. Just an arm for now but I guess it's time to show you guys something. Stay tuned.

On-set tips: Creating high frequency detail / May 25, 2017 by Xuan Prada

In a previous post I mentioned the importance of having high frequency details whilst scanning assets on-set. Sometimes if we don't have that detail we can just create it. Actually sometimes this is the only way to capture volumes and surfaces efficiently, specially if the asset doesn't have any surface detail, like white objects for example.

If we are dealing with assets that are being used on set but won't appear in the final edit, it is probably that those assets are not painted at all. There is no need to spend resources on it, right? But we might need to scan those assets to create a virtual asset that will be ultimately used on screen.

As mentioned before, if we don't have enough surface detail it will be so difficult to scan assets using photogrammetry so, we need to create high frequency detail on our own way.

Let's say we need to create a virtual assets of this physical mask. It is completely plain, white, we don't see much detail on its surface. We can create high frequency detail just painting some dots, or placing small stickers across the surface.

In this particular case I'm using a regular DSLR + multi zoom lens. A tripod, a support for the mask and some washable paint. I prefer to use small round stickers because they create less artifacts in the scan, but I run out of them.

I created this support while ago to scan fruits and other organic assets.

The first thing I usually do (if the object is white) is covering the whole object with neutral gray paint. It is way more easy to balance the exposure photographing again gray than white.

Once the gray paint is dry I just paint small dots or place the round stickers to create high frequency detail. The smallest the better.

Once the material has been processed you should get a pretty decent scan. Probably an impossible task without creating all the high frequency detail first.

From scan to asset / March 20, 2017 by Xuan Prada

In this video I will show you my process to convert 3D scans into assets ready for production. I believe the audio is in Spanish so, feel free to mute it or try to learn some Cervantes language :)

On-set tips: The importance of high frequency detail / December 13, 2016 by Xuan Prada

Quick tip here. Whenever possible use some kind of high frequency detail to capture references for your assets. In this scenario I'm scanning with photos this huge rock, with only 50 images and very bad conditions. Low lighting situation, shot hand-held, no tripod at all, very windy and raining.
Thanks to all the great high frequency detail on the surface of this rock the output is quite good to use as modeling reference, even to extract highly detailed displacement maps.

Notice in the image below that I'm using only 50 pictures. Not much you might say. But thanks to all the tiny detail the photogrammetry software does very well reconstructing the point cloud to generate the 3D model. There is a lot of information to find common points between photos.

The shooting pattern couldn't be more simple. Just one eight all around the subject. The alignment was completely successfully in Photoscan.

As you can see here, even with a small number of photos and not the best lighting conditions, the output is quite good.

I did an automatic retopology in Zbrush. I don't care much about the topology, this asset is not going to be animated at all. I just need a manageable topology to create a nice uv mapping and reproject all the fine detail in Zbrush and use it later as displacement map.

A few render tests.

UV to Mesh / December 8, 2016 by Xuan Prada

Mi friend David Munoz Velazquez just pointed me to this great script to flatten geometries based on UV Mapping, pretty useful for re-topology tasks. In this demo I use it to create nice topology for 3D garments in Marvelous Designer. Then I can apply any new simulation changes to the final mesh using morphs. Check it out.

Clarisse shading layers: Crowd in 5 minutes / October 24, 2016 by Xuan Prada

One feature that I really like in Clarisse are the shading layers. With them you can drive shaders based on naming convention or location of assets in the scene. With this method you can assign shaders to a very complex scene structure in no time. In this particular case I'll be showing you how to shade an entire army and create shading/texturing variations in just a few minutes.

I'll be using an alembic cache simulation exported from Maya using Golaem. Usually you will get thousand of objects with different naming convention, which makes the shading assignment task a bit laborious. With shading layer rules in Clarisse we can speed up a lot this tedious process

Import an alembic cache with the crowd simulation through file -> import -> scene

In this scene I have 1518 different objects.

I'm going to create an IBL rig with one of my HDRIs to get some decent lighting in the scene.

I created a new context called geometry where I placed the army and also created a ground plane.
I also created another context called shaders where I'm going to place all my shaders for the soldiers.
In the shaders context I created a new material called dummy, just a lambertian grey shader.
We are going to be using shading layers, to apply shaders globally based on context and naming convention. I created a shading layers called army (new -> shading layer).
With the pass (image) selected, select the 3D layer and apply the shading layer.

Using the shading layer editor, add a new rule to apply the dummy shader to everything in the scene.

I'm going to add a rule for everything called heavyArmor.
Then just configure the shader for the heavyArmour with metal properties and it's correspondent textures.

Create a new rule for the helmets and apply the shader that contains the proper textures for the helmets.

I keep adding rules and shaders for different parts of the sodliers.
If I want to create random variation, I can create shading layers for specific names of parts or even easier and faster, I can put a few items in a new context and create a new shading rule for them. For the bodies I want to use caucasian and black skin soldiers. I grabbed a few bodies and place them inside a new context called black. Then create a new shading rules where I apply a shader with different skin textures to all the bodies in that context.

I repeated the same process for the shields and other elements.

At the end of the process I can have a very populated army with a lot of random texture variations in just a few minutes.
This is how my shading layers look like at the end of the process.

UDIM workflow in Nuke / September 26, 2016 by Xuan Prada

Texture artists, matte painters and environment artists often have to deal with UDIMs in Nuke. This is a very basic template that hopefully can illustrate how we usually handle this situation.

Cons

Slower than using Mari. Each UDIM is treated individually.
No virtual texturing, slower workflow. Yes, you can use Nuke's proxies but they are not as good as virtual texturing.

Pros

No paint buffer dependant. Always the best resolution available.
Non destructive workflow, nodes!
Save around £1,233 on Mari's license.

Workflow

I'll be using this simple footage as base for my matte.
We need to project this in Nuke and bake it on to different UDIMs to use it later in a 3D package.

As geometry support I'm using this plane with 5 UDIMs.

In Nuke, import the geometry support and the footage.
Create a camera.
Connect the camera and footage using a Project 3D node.

Disable the crop option of the Project 3D node. If not the proejctions wouldn't go any further than UV range 0-1.

Use a UV Tile node to point to the UDIM that you need to work on.

Connect the img input of the UV Tile node to the geometry support.

Use a UV Project node to connect the camera and the geometry support.
Set projection to off.

Import the camera of the shot.

Look through the camera in the 3D view and the matte should be projected on to the geometry support.

Connect a Scanline Render to the UV Project.
Set the projection model to UV.
In the 2D view you should see the UDIM projection that we set previously.

If you need to work with a different UDIM just change the UV Tile.

So this is the basic setup. Do whatever you need in between like projections, painting and so on to finish your matte.
Then export all your UDIMs individually as texture maps to be used in the 3D software.
Here I just rendered the UDIMs extracted from Nuke in Maya/Arnold.

rendering Maya particles in Clarisse / November 23, 2015 by Xuan Prada

This is a very simple tutorial explaining how to render particle systems simulated in Maya inside Isotropix Clarisse. I already have a few posts about using Clarisse for different purposes, if you check by the tag "Clarisse" you will find all the previous posts. Hope to be publishing more soon.

In this particular case we'll be using a very simple particle system in Maya. We are going to export it to Clarisse and use custom geometries and Clarisse's powerful scatterer system to render millions of polygons very fast and nicely.

Once your particle system has been simulated in Maya, export it via Alembic. One of the standard 3D formats for exchanging information in VFX.

Create an IBL rig in Clarisse. In a previous post I explain how to do it, it is quite simple.

With Clarisse 2.0 it is so simple to do, just one click and you are ready to go.

Go to File -> Import -> Scene and select the Alembic file exported from Maya.
It comes with 2 types of particles, a grid acting as ground and the render camera.

Create a few contexts to keep everything tidy. Geo, particles, cameras and materials.

In the geo context I imported the toy_man and the toy_truck models (.obj) and moved the grid from the main context to the geo context.
Moved the 2 particles systems and the camera to their correspondent contexts.

In the materials context I created 2 materials and 2 color textures for the models. Very simple shaders and textures.

In the particles context I created a new scatterer calle scatterer_typeA.

In the geometry support of the scatter add the particles_typeA and in the geometry section add the toy_man model.
I’m also adding some variation to the rotation.

If I move my timeline I will see the particle animation using the toy_man model.

Do not forget to assign the material created before.

Create another scatterer for the partycles_typeB and configure the geometry support and the geometry to be used.
Add also some rotation and position variation.

As these models are quite big compared with the toy figurine, I’m offsetting the particle effect to reduce the presence of toy_trucks in the scene.

Before rendering, I’d like to add some motion blur to the scene. Go to raytracer -> Motion Blur -> 3D motion blur. Now you are ready to render the whole animation.

mmColorTarget / August 18, 2015 by Xuan Prada

This is a very quick demo of how to install on Mac and use the gizmo mmColorTarget or at least how I use it for my texturing/references and lighting process. The gizmo itself was created by Marco Meyer.

VFX footage input/output / January 30, 2015 by Xuan Prada

This is a very quick and dirty explanation of how the footage and specially colour is managed in a VFX facility.

Shooting camera to Lab
The RAW material recorded on-set goes to the lab. In the lab it is converted to .dpx which is the standard film format. Sometimes the might use exr but it's not that common.
A lot of movies are still being filmed with film cameras, in those cases the lab will scan the negatives and convert them to .dpx to be used along the pipeline.

Shooting camera to Dailies
The RAW material recorded on-set goes to dailies. The cinematographer, DP, or DI applies a primary LUT or color grading to be used along the project.
Original scans with LUT applied are converted to low quality scans and .mov files are generated for distribution.

Dailies to Editorial
Editorial department receive the low quality scans (Quicktimes) with the LUT applied.
They use these files to make the initial cuts and bidding.

Editorial to VFX
VFX facilities receive the low quality scans (Quictimes) with LUT applied. They use these files for bidding.
Later on they will use them as reference for color grading.

Lab to VFX
Lab provides high quality scans to the VFX facility. This is pretty much RAW material and the LUT needs to be applied.
The VFX facility will have to apply the LUT's film to the work done by scratch by them.
When the VFX work is done, the VFX facility renders out exr files.

VFX to DI
DI will do the final grading to match the Editorial Quicktimes.

VFX/DI to Editorial
High quality material produced by the VFX facility goes to Editorial to be inserted in the cuts.

The basic practical workflow would be.

Read raw scan data.
Read Quicktime scan data.
Dpx scans usually are in LOG color space.
Exr scans usually are in LIN color space.
Apply LUT and other color grading to the RAW scans to match the Quicktime scans.
Render out to Editorial using the same color space used for bringing in footage.
Render out Quicktimes using the same color space used for viewing. If wathcing for excample in sRGB you will have to bake the LUT.
Good Quicktime settings: Colorspace sRGB, Codec Avid Dnx HD, 23.98 frames, depth million of colors, RGB levels, no alpha, 1080p/23.976 Dnx HD 36 8bit

Cubes tutorial / October 22, 2014 by Xuan Prada

A few months ago, when my workmates from Double Negative were working on Transcendence, I saw them using Houdini to create such a beautiful animations using tiny geometries. They were like millions of small cubes building shapes and forms.
Some time later other people started doing similar stuff with Maya's XGen and other tools. I tried it and it works like a charm.

I was curious about these images and then decided to recreate something similar, but I wanted to do it in a simpler and quicker way. I found out that combining Cinema 4D and Maya is probably the easiest way to create this effect.

If you have any clue to do the same in Modo or Softimage, please let me know, I'm really curious.
This is my current approach.

In Cinema 4D create a plane with a lot of subdivisions. Each one of those subdivisions will generate a cube. In this case I’m using a 1000cm x 1000cm plane with 500 subdivisions.

Create a new material and assign it to the plane.

Select the plane and go to the menu Simulate -> Hair objects -> Add hair.

If you zoom in you will see that one hair guide is generated by each vertex of the plane.

In the hair options reduce the segments guides to 1 because we just need straight guides we don’t care about hair resolution.
Also change the root to polygon center. Now the guides growth from each polygon center instead of each vertex of the plane.

Remove the option render hair (we are not going to be rendering hairs) from the generate tab. Also switch the type to square.

Right now we can see cubes instead of hair guides, but they are so thin.

We can control the thickness using the hair material. In this case I’m using 1.9 cm

Next thing would be randomising the height. Using a procedural noise would be enough to get nice results. We can also create animations very quickly, just play with the noise values.

Remove the noise for now. We want to control the length using a bitmap.
Also hide the hair, it’s quicker to setup if we don’t see the hair in viewport.
In the Plane material, go to luminance and select a bitmap. Adjust the UV Mapping to place the bitmap in your desired place.

In the hair material, use the same image for the length parameter.
Copy the same uv coordinates from the plane material.

Add a pixel effect to the texture and type the number of pixels based on the resolution of the plane. In this case 500

Do this in both materials, the plane and the hair. Now each cube will be mapped with a small portion of the bitmap.
Display the hair system and voila, that’s it.

Obviously the greater contrast in your image the better. I strongly recommend you to use high dynamic range images, as you know the contrast ratio is huge compared with low dynamic images.
At this point you can render it here in C4D or just export the geometry to another 3D software and render engine.
Select the hair system and make it editable. Now you are ready to export it as .obj

Import the .obj in your favourite 3D software. Then apply your lighting and shaders, and connect the image that you used before to generate the hair system. Of course, you can control the color of the hair system using any other bitmap or procedurals.

In order to keep this work very simple, I’m just rendering a beauty pass and an ambient occlusion pass, but of course you can render as many aov’s as you need.

I also animate very quickly the translation of the hair system and added motion blur and depth of field to the camera to get a more dynamic image, but this is really up to you.
This is just the tip of the iceberg, with this quick and easy technique you can create beautiful images combining it with your expertise.

Photography assembly for matte painters / October 1, 2014 by Xuan Prada

In this post I'm going to explain my methodology to merge different pictures or portions of an environment in order to create a panoramic image to be used for matte painting purposes. I'm not talking about creating equirectangular panoramas for 3D lighting, for that I use ptGui and there is not a better tool for it.

I'm talking about blending different images or footage (video) to create a seamless panoramic image ready to use in any 3D or 2D program. It can be composed using only 2 images or maybe 15, it doesn't matter.
This method is much more complicated and requires more human time than using ptGui or any other stitching software. But the power of this method is that you can use it with HDR footage recorded with a Blackmagic camera, for example.

The pictures that I'm using for this tutorial were taken with a nodal point base, but they are not calibrated or similar. In fact they don't need to be like that. Obviously taking pictures from a nodal point rotation base will help a lot, but the good thing of this technique is that you can use different angles taken from different positions and also using different focal and different film backs from various digital cameras.

I'm using these 7 images taken from a bridge in Chiswick, West London. The resolution of the images is 7000px wide so I created a proxy version around 3000px wide.
All the pictures were taken with same focal, same exposure and with the ISO and White Balance locked.

We need to know some information about these pictures. In order to blend the images in to a panoramic image we need to know the focal length and the film back or sensor size.
Connect a view meta data node to every single image to check this information. In this case I was the person who took the photos, so I know all of them have the same settings, but if you are not sure about the settings, check one by one.
I can see that the focal length is 280/10 which means the images were taken using a 28mm lens.
I don't see film back information but I do see the camera model, a Nikon D800. If I google the film back for this camera I see that the size is 35.9mm x 24mm.

Create a camera node with the information of the film back and the focal length.

At this point it would be a good idea to correct the lens distortion in your images. You can use a lens distortion node in Nuke if you shot a lens distortion grid, or just do eyeballing.
In my case I'm using the great lens distortion tools in Adobe Lightroom, but this is only possible because I'm using stills. You should always shot lens distortion grids.

Connect a card node to the image and remove all the subdivisions.
Also deactivate the image aspect to have 1:1 cards. We will fix this later.

Connect a transfer geo node to the card, and it's axis input to the camera.
If we move the camera, the card is attached to it all the time.

Now we are about to create a custom parameter to keep the card aligned to the camera all the time, with the correct focal length and film back. Even if we play with the camera parameters, the image will be updated automatically.
In the transform geo parameters, RMB and select manage user knobs and add a floating point slider. Call it distance. Set the min to 0 and the max to 10
This will allow us to place the card in space always relative to the camera.

In the transform geo translate z press = to type an expression. write -distance
Now if we play with the custom distance value it works.

Now we have to refer to the film back and focal length so the card matches the camera information when it's moved or rotated.
In the x scale of the transform geo node type this expression (input1.haperture/input1.focal)*distance and in the y scale type: (input1.vaperture/input1.focal)*distance being input1 the camera axis.
Now if we play with the distance custom parameter everything is perfectly aligned.

Create a group with the card, camera and transfer geo nodes.
Remove the input2 and input3 and connect the input1 to the card instead of the camera.

Go out of the group and connect it to the image. There are usually refreshing issues so cut the whole group node and paste it. This will fix the problem.

Manage knobs here and pick the focal length and film back from the camera (just for checking purposes)
Also pick the rotation from the camera and the distance from the transfer geo.
Having these controls here we won't have to go inside of the group if we need to use them. And we will.

Create a project 3D node and connect the camera to the camera input and the input1 to the input.

Create a sitch node below the transfer geo node and connect the input1 to the project3D node.

Add another custom control to the group parameters. Use the pulldown choice, call it mode and add two lines: card and project 3D.

In the switch node add an expression: parent.mode

Put the mode to project 3D.
Add a sphere node, scale it big and connect it to the camera projector.
You will se the image projected in the sphere instead of being rendered in a flat card.

Depending on your pipeline and your workflow you may want to use cards or projectors. At some point you will need both of them, so is nice to have quick controls to switch between them

In this tutorial we are going to use the card mode. For now leave it as card and remove the sphere.

Set the camera in the viewport and lock it.
Now you can zoom in and out without loosing the camera.

Set the horizon line playing with the rotation.

Copy and paste the camera projector group and set the horizon in the next image by doing the same than before; locking the camera and playing with camera rotation.

Create a scene node and add both images. Check that all the images have an alpha channel. Auto alpha should be fine as long as the alpha is completely white.
Look through the camera of the first camera projector and lock the viewport. Zoom out and start playing with the rotation and distance of the second camera projection until both images are perfectly blended.

Repeat the process with every single image. Just do the same than before; look through the previous camera, lock it, zoom out and play with the controls of the next image until they are perfectly aligned.

Create a camera node and call it shot camera.
Create a scanline render node.
Create a reformat node and type the format of your shot. In this case I'm using a super 35 format which means 1920x817
Connect the obj/scene input of the scanline render to the scene node.
Connect the camera input of the scanline render to the shot camera.
Connect the reformat node to the bg input of the scanline render node.
Look through the scanline render in 2D and you will see the panorama through the shot camera.
Play with the rotation of the camera in order to place the panorama in the desired position.

That's it if you only need to see the panorama through the shot camera. But let's say you also need to project it in a 3D space.

Create another scanline render node and change the projection mode to spherical. Connect it to the scene.
Create a reformat node with an equirectangular format and connect it to the bg input of the scanline render. In this case I'm using a 4000x2000 format.

Create a sphere node and connect it to the spherical scanline render. Put a mirror node in between to invert the normal of the sphere.
Create another scanline render and connect it's camera input to the shot camera.
Connect the bg input of the new scanline render to the shot reformat node (super 35).
Connect the scn/obj of the new scanline render and connect it to the sphere node.
That's all that you need.
You can look through the scanline render in the 2D and 3D viewport. We got all the images projected in 3D and rendered through the shot camera.

You can download the sample scene here.

Upcoming VFX films / August 1, 2014 by Xuan Prada

2014

Deliver Us From Evil 07/02/2014
Dawn of the Planet of the Apes 07/11/2014
I Origins 07/18/14
Mood Indigo 07/18/14
Hercules 07/25/2014
Lucy 07/25/2014
Guardians of the Galaxy 08/01/2014
Into the Storm 08/08/2014
Teenage Mutant Ninja Turtles 08/08/2014
James Cameron's Deepsea Challenge 3D 08/08/2014
The Giver 08/15/2014
As Above, So Below 08/15/2014
Ragnarok 08/15/2014
Sin City: A Dame to Kill For 08/22/2014
The Congress 08/29/2014
The Zero Theorem 09/19/14
The Maze Runner 09/19/2014
The Boxtrolls 09/26/2014
Gone Girl 10/03/2014
Left Behind 10/03/2014
The Interview 10/10/2014
Birdman 10/17/14
Dracula Untold 10/17/2014
Kingsman: The Secret Service 10/24/2014
Horns 10/31/14
Interstellar 11/07/2014
Fury 11/14/2014
The Hunger Games: Mockingjay - Part I 11/21/2014
The Imitation Game 11/21/2014
The Pyramid 12/09/2014
Exodus: Gods and Kings 12/12/2014
The Hobbit: The Battle of the Five Armies 12/17/2014
Annie 12/19/14
Night at the Museum: Secret of the Tomb 12/19/2014
Into the Woods 12/25/2014
Paddington 12/25/2014
Unbroken 12/25/2014
Harbinger Down 2014
Space Station 76 2014

2015

Kitchen Sink 01/09/2015
Inherent Vice 01/09/2015
The Man From U.N.C.L.E. 01/16/2015
Cyber 01/16/2015
Ex Machina 01/23/2015
Black Sea 01/23/2015
Seventh Son 02/06/2015
Jupiter Ascending 02/06/2015
Poltergeist 02/13/2015
Selfless 02/27/2015
Chappie 03/06/2015
Heart of the Sea 03/13/2015
Cinderella 03/15/2015
Insurgent 03/20/2015
Fast and Furious 7 04/10/2015
Avengers: Age of Ultron 05/01/2015
Mad Max: Fury Road 05/15/2015
Pixels 05/15/2015
Tomorrowland 05/22/2015
Untitled Cameron Crowe Project 05/29/2015
San Andreas 06/05/2015
Jurassic World 06/12/2015
The Fantastic Four 06/19/2015
Ted 2 06/26/2015
Terminator: Genesis 07/01/2015
Pan 07/17/15
Ant-Man 07/17/2015
Victor Frankenstein 10/02/15
The Walk 10/02/15
The Jungle Book 10/09/15
Crimson Peak 10/16/2015
The Hunger Games: Mockingjay - Part 2 11/20/2015
Star Wars: Episode VII 12/18/2015
The Lobster 2015

2016

Gods of Egypt 02/12/2016
Warcraft 03/11/2016
Batman v Superman: Dawn of Justice 05/06/2016
Captain America 3 05/06/2016
The Sinster Six 11/11/2016
Avatar 2 December 2016

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