Vray Dirt Tutorial

A quick tutorial on adding dirt to specific materials in Vray. A very useful application of the vraydirt shader in Vray is to make materials look dirty/weathered. Used in it's basic form, with default settings, vraydirt can be used to add a general darkening around edges/corners in your 3d model. It can also be modified to affect only areas directly below 3d features.

a - Shows vraydirt using it's default settings (dirt equal on all sides) b - Shows vraydirt using settings to force the dirt to work only in a downward direction c - As b, but with 'invert normal' ticked d - b and c used within a vraycomptex map, set to minimum

By experimenting with the distribution, falloff and z-bias values, I managed to get the downward effect I was looking for (exact settings in screen grab below). I then combine 2 versions of the vraydirt map inside a vraycomptex map. The first version is for concave creases, the other for convex creases by ticking 'invert normal'. The vraycomptex map is set to minimum so that it combines the two maps by always using the darkest rgb value.

Above is a render with a concrete material demonstrating the effect. In this case, the occluded map is the same as the unoccluded map but darker and with a slight rusty hue (achieved using a color correction map).

The diagram below shows how the material is made up, and shows the values I used:

To take this a step further, you could additionally add a map to vary the radius of the vraydirt effect. (Note that the value I used for radius is in mm)

And finally an animated gif showing renders with and without the vraydirt:

Chelsea Square Day

A new project in my vizualisation gallery: Chelsea Square by Wilkinson King Architects. These images were for marketing purposes and were lots of fun to work on. The building was modeled in Sketchup and all textures were made from scratch from photographs. As usual with my projects, there wasn't much post work in photoshop (apart from the cross section).

The caustics in the pool were calculated with all the glass hidden, saved and then the glass was turned back on for the final render. The actual water surface was modeled by dropping a ball into some reactor water, totally over the top I know!

I wanted the brick texture to match the existing building as closely as possible so I took photos of the end gable brick (in the shade) and then painted over every brick in photoshop. This was so that the displacement map worked correctly in displacing the bricks outwards while recessing the grout slightly, and also helped in the reflection map to make the grout less reflective. The traced bricks layer was used as a mask to lighten a greyscale copy of the diffuse layer. Painting over bricks in photoshop is as about as boring as it gets, but worth the effort.

vrayRT for Architectural Visualisation

10min demo of VrayRT for Architectural Visualisation

Very impressed with vrayRT so far, looks like it will be really useful for a lot of my work. Here's a 10min (longer than intended!) demonstration on vimeo (no sound). VrayRT is using my macpro (2.8 octo) and a slave i7 920.

3d trees

A collection of broadleaf trees that I made in onyxtree and further modified in 3dsmax. I'm currently looking at investing in growfx as well, seems to have a bit of a steep learning curve but might eventually suit my workflow better than onyxtree. Large Sugar Maple

Ash

Young Sugar Maple

Sugar Maple

White Oak

Vray grass tutorial part 2

Before I get on to the material settings for the grass I'm going to show how I used similar techniques as in part 1 to make shorter grass. This time, I made 5 new individual blades, and made them a lot smaller, more random and also gave them a texture.

I made 3 lengths of grass, the longer ones had taller, less curved, blades. These were then scattered about 1000 times onto a 500mm dia. circle using advanced painter in randomize mode. The next step was to attach all blades into one editable mesh/poly and reset the xform, this seems to be vitally important before exporting it as a vrayproxy. Before I did this, the vrayproxy was using huge amounts of memory when rendering.

Short grass

Longer grass - some stats: approx 8000 polys per proxy x 1000 proxies = approx 8 million total polygons. 3dsmax uses about 2 gig memory for this scene and each view rendered pretty quickly considering I had vrayfog and depth of field on.

Note: I use vrayscatter (a commercial plugin but well worth the money) to scatter the proxies. There are lots of tutorials for it here. You can also use scatter by Peter Watje, advanced painter, Forest by Itoosoft, Groundwiz Planter or 3dsmax particles.

Material set up:

The main material for the grass is a multi-sub object with 3 materials within it. Each of the original 5 blades of grass were assigned one of these material IDs at random before they were scattered. Each material is a vraymaterial within a vray2sidedmaterial. Hopefully the screenshots are enough to describe the set up. The three sub materials are all essentially the same, and use the same Bitmap, but use a color correction map to subtly shift the colour (hue). The vray2sided material gives the SSS effect, and is the best option for thin geometry (no thickness) like grass and tree leaves.

You can optionally try turning off 'trace reflections' to try speeding things up. This means the grass will still pick up highlights from the sun, but won't pick up proper reflections, like the colour of the sky. I found the speed increase to be hardly noticeable in my tests, and it just didn't look as good.

UPDATE:

There's nothing special about my render settings or scene set up for this scene, just a vraysun & sky, vrayphysical camera and my usual colour mapping settings. To make the renders look a bit more interesting I decided to play a bit with sun and shadow, and also back lit the grass so that the transparent effect was evident. As you can see from the screengrab below, I have the sun coming from slightly behind the brick wall, and it is also very low in the sky. When experimenting with materials it's very important to set your scene up to mimic an effect you would see in the real world.

If you are interested in downloading an example scene, please visit the tutorials section of vray.info and navigate to the 2nd part of my grass tutorial.

architectural photography

New recently completed project in the photography gallery for Ian Springford Architects.

Typical processing workflow is something like:

- compare all bracketed exposures in Adobe Lightroom, flag the most likely ones, eventually end up with the best one - adjust exposure, white balance - remove chromatic aberration, vignetting - remove sensor dust spots with spotting tool - export tiff to ptlens, correct any distortion & perspective - back to Lightroom, final crop

Thankfully Lightroom takes most of the pain out of doing this to 250 odd shots, I just wish it was possible to do distortion correction on a dng without converting to a tiff.

HDR Skydome Tutorial

For the 7 shots used to make this HDR skydome I used a Canon 1ds mk3 which has superb auto bracketing abilities as well as being very fast and having 21 megapixels. The lens used for these shots was a sigma 8mm fisheye which gives a complete circular image on a full frame dslr. I set the AEB to 7 shots 2 stops apart, which gave exposure times of 0.5s, 1/8, 1/30, 1/125, 1/500, 1/2000 & 1/8000 all at F20. This range of exposures is crucial for capturing the full dynamic range of the sun, which will eventually mean you get good strong shadows when you use the HDR image to light a 3d scene.

- Process raw files to remove chromatic aberration & to ensure white balance is consistent. I do this in Adobe Lightroom (pictured below), where you can copy the develop settings from the first file, and then batch process the remaining ones to save time.

- Export as 16 bit TIFFs

- Load TIFFs into Photomatix or Photoshop to blend into a single HDR, I use Photomatix as it seems to do a better job of removing ghosting artifacts (from moving clouds).

- Load HDR image file into Hugin. Choose lens type as fisheye when importing, and set the Horizontal field of view to 285 degrees (I arrived at this mostly through trial and error!)

- Hugin will complain that more than 1 image is required - ignore.

- Set pitch of image to 90, and adjust yaw so that sun is centred. If you know where the sun is, it helps later on when you come to rotating the skydome in your 3d application.

- in the stitcher tab, I take off soft blending as there is only 1 image, and press the 'calculate optimal size' button. Then hit 'Stitch Now!' (saving as a tif)

- Open 32bit tif in photoshop, clone out anything you dont want (dust in my case), save as 32 bit exr. Image below shows how the HDR should look when you drag the exposure slider in photoshop.

Sometime, I'll follow this up with something about how I use these in 3dsmax & Vray!

vray override material

The vray override material is a great way of previewing/checking your lighting even when you are a long way into a project. The scene below uses a homemade dusk HDR skydome and vrayIES internal lights which have a colour temperature of 4500 (6000 in the second image) kelvin. I wanted to check the effect 2 alternative IES web files made to the internal lighting in distribution as well as the fancy patterns on the walls. I find having all the materials a neutral colour really helps in balancing natural & artificial light.

To set it up, you first make a mid grey material in the material editor and then drag it into the vray override mtl slot in global switches (in this instance I made a material called '200' which has the rgb values 200,200,200):

then you can specify which objects to exclude from the override material (normally glass) in the include/exclude dialog:

Vray grass tutorial part 1

Or more specifically how to create a field of grass using vray proxy objects and the vrayscatter plugin. Software used: 3dstudio Max, vray (should work with mentalray proxies too), vrayscatter (for alternatives see below), advanced painter (free script)

The first stage is to create some individual blades of grass and then make a small area of grass that can later be distributed thousands of times onto your terrain.

The 3 individual blades of grass were modeled as a plane object with 8x1 segments, collapsed to an editable poly and then I moved the vertices into position in the left and front viewports. You could use a bend modifier as well, just make sure the final object has as few polygons as you can get away with.

I then used a very handy script called advanced painter to 'paint' about 100 blades of grass over a 1m x 1m plane object. Set advanced painter to randomize mode, tell it to scatter as copies (not instances), pick the 3 blades of grass as the objects to be scattered and set the min and max scale and z rotation values to something like 0.75 - 1.25 and -45deg +45deg. Then select the plane object, click paint and paint the grass on until it looks like a natural clump of grass. I usually scatter some smaller blades round the circumference of the circle to the clumps blend together better when rendered. Instead of adv. painter, you could also use the 3dsmax compound scatter object, scatter by Peter Watjes, or just do it by hand!

The final stage here, before exporting as a vrayproxy, is to make sure your blades of grass aren't instances, otherwise you will run into problems later on. I normally collapse all the blades into one object (make one blade unique then attach all other blades to it when in editable poly mode). You could do a reset xform too, for good measure. Another thing I did was to apply a box Uvw map to it before I collapsed it, as I wanted to make the tips of the grass lighter. Right click on the mesh and choose the export to vray proxy option to save it as a vrmesh file.

Now comes the fun part! Choose vrayscatter from create/vray and place it somewhere in your scene. Switch to the edit panel and load up the vrmesh you made in the earlier steps. Then you need to choose your terrain object and at that point you should see lots of boxes being scattered over your terrain.

There are alternatives to vrayscatter as well:

- The makers of vrayscatter are currently working on a new product called multiscatter which will supersede vrayscatter and will also support mentalray proxies. - Forest by Itoosoft is apparently very capable, and there is a free version so well worth trying out. - Groundwiz Planter can use vray/mr proxies - you can just as easily use the free advanced painter script to distribute the proxies once you have made them. It might take a while though, and your viewport will probably slow down after a while - you could distribute the proxies using 3dsmax particles

Check out part two of this tutorial where I use similar techniques to make shorter grass and go over the material set up for the grass blades. If there's anything you'd like to see covered in future feel free to make requests in the comments.

Vray Edge Fillet Tutorial

This is a quick tutorial to show how I add extra details to the edges of surfaces. In this scene, I wanted to make the hard edges of the concrete appear rougher and less uniform. Vray comes with a map called a vrayedgestex map that you would normally use to make wireframe materials (eg hidden line renders). It can also be used as a bump map to give the illusion of rounded edges.

In the 3 examples below, I have applied a vrayedgestex (red for clarity) to the diffuse channel of a grey material, the second is a black and white noise map, and in the third I have combined the two by using a vraycomptex map. The vraycomptex map is set to multiply which gives the effect of breaking up the otherwise smooth red line around all the edges of the table. Setting the vraycomptex to multiply is like blending modes in Photoshop, and about as easy to understand - I recommend experimenting with the various modes till you get a feeling for what each do.

In the animated gif, 1 is a render without any bump map, 2 is with just vrayedgestex and 3 is the final result.

So in the material editor, at the top I have a vraycomptex in the bump slot called 'edge01' which adds together the next vraycomptex 'edge02' and the standard bitmap bump jpg for the concrete material. 'edge02'  is the one that multiplies together the vrayedgestex map and the noise map. You should set the vrayedgestex to white, and change it to world units. I work in millimeters so 2.5 was about right. You can then play about with different types of noise maps, but the settings I have above worked well for concrete.