Tips and tricks: Corona LightMixer

Simon just posted a nice round up on his blog of a new Corona Renderer feature called LightMixer which we thought we would share here.

Hi guys,

This time it’s really worth it to download the latest daily build of Corona Renderer. Recently the gents behind it introduced an awesome feature called LightMixer. Up until now similar stuff was only available in Maxwell and Fryrender (is that still being developed?!), but right now everyone will have access to this incredible thing. Below you’ll find a short how-to and you’ll also find my notes to that video right underneath.
Ok, based on this video I’m sure you already have a pretty good idea about how this works, but just in case I’ll do a small run down.

What is it? Basically Corona LightMixer allows you to control the power of your light sources straight in the frame buffer. It works with both interactive and “regular” rendering so it can be pretty useful.

How it works? Looking at the video above I’m sure you’ve already noticed that it’s basically a render pass, very similar to VrayLightSelect, but one that allows you to control it’s multiplier straight in the framebuffer, instead creating a need to comp it in postproduction.

To get LightMixer working you have to create a new CShading_LightSelect pass, scroll down and add all the light sources that you want to control in this particular group, to the Light Select Render Element list by pressing “+” and selecting each light individually.

IMPORTANT! LightSelect pass does not care about instances. If you have 100 lights that are all instanced, you have to select all of them.

The amazing thing is that LightMixer also allows you to change the color of your light sources, but in the end, and this is an important one, you have to remember that this is just a postproduction gimmick, basically combining together different LightSelect passes like you would in photoshop, it won’t change anything in your scene, which means that as soon as you’ll reset your frame buffer to defaults or merge those lights into a new scene, you’ll have to go through that entire process once again.

Jobs at The Boundary

A quick reminder that we are always on the lookout for suitable people to join our team here at The Boundary. Send us an email with a CV and portfolio to

All levels of experience will be considered, enthusiasm to do great work is the most important attribute.

You should be eligible to work in the UK.

Expanding The Boundary

Join us at The Boundary!

We are looking for talented, creative and motivated 3d artists to join our expanding team.

Applicants from a 3d viz background should have a strong interest in architecture and photography and be keen to develop new skills in line with the ever evolving requirements of the industry.

Applicants from an architecture background should be familiar with 3ds Max and rendering and be keen to work on projects with the world's most celebrated architects.

Full time position. No freelancers or agencies. Applicants must be legally employable in the UK and be available to work with the team at our North London studio. 

Please send a CV and portfolio to


We are offering a huge 50% everything in The Boundary Store for Black Friday all the way through to end of day on Cyber Monday with the code BLACK50 , enjoy!

The above image was rendered in Corona (which handles god rays beautifully). A reminder that when we make Corona versions of the scenes, people who have already purchased will get the corona version as a free update.

Boundary Scene 02


Here is the second scene to be made available on the Boundary Store.  This one includes several detailed furniture models including Hans Wegner's CH24 Y-Chair and Mendes da Rocha's Paulistano armchair.  Check the Boundary Blog for up coming tutorials on the making of this scene including the spherical panoramic view above.  For the first week we are offering a 20% discount on this scene:

Discount code: STAITHE END
Expires Friday 30th Oct 2015


Super House

Here's a little project which we have been working on for the past six months.  It's a luxury concept house aimed at the super rich as the perfect accompaniment to a Super Yacht!  We've had lots of fun and games with this one as our close relationship with Strom Architects gave us the freedom to create our own Mediterranean paradise.  The aim was to produce a complete 3d environment free from any compositing with minimal post providing a platform for testing 360's, animation and varying moods.  Hope you enjoy the result and if anyone has the odd £30m or so going spare give Strom Architects a call.

Click here for full image gallery

Super House website

SoA Acadamy Day 06

Just received these pics from Gianpiero of our talk at the State of Art Academy Day 06.  Phil here suggested that with our matching Boundary attire we look like a beach volleyball team in a post match press conference.

Carey House tutorial 09 - Post Production


In this, the final part of the making of the Carey House tutorial series, we are taking a brief look at post production.  This is an aspect of our workflow which varies from project to project but is always something we try to keep to a minimum preferring to rely as much as possible on getting the image correct in the 3d environment rather than using render elements and painting in detail in Photoshop.

Base render

Although this is the base render we generally apply some curves in the vray frame buffer prior to saving out.  This is just a preference and can all be done in Photoshop if preferred.  

Photoshop layers

There are two basic elements to our post workflow; Camera Raw Filter and a few adjustment layers.  Sometimes we have more adjustment layers including saturation and colour balance, we have found recently however that much of this can be done in the Camera Raw Filter.

As the Camera Raw Filter can currently not be used as an adjustment layer we start by converting the base render to a smart object so the adjustments are not destructive.  In this case under the Basic tab a little clarity has been given and a small amount of highlight compression to bring out some of the details in the bright sky.  A few other tweaks have been made to the shadows and whites to balance the image.

Camera Raw Filter Basic tab

Under the Effects tab a small amount of Post Crop Vignetting is given set to Highlight Priority style.  This is useful as it prevents bright areas of the sky usually in the top corners of the image from becoming overly dark and muddy looking. 

Camera Raw Filter Effects tab

with camera RAW adjustments

Following the overall Camera Raw adjustments a few basic curves have been used to highlight certain areas of the image.  The first one darkens the sky slightly, the second brightens the foreground vegetation and the third increases the contrast of the building itself. 

Final image with Camera Raw + Curves

If anyone thinks that having a closer look at this Photoshop file would be useful, let us know and we will make it available as a free download on The Boundary Store.


Carey House tutorial 08 - Atmosphere

In this tutorial we will look at the finishing touches to the scene prior to final render. VRayEnvironmentFog is used in all of our scenes to some extent even if only very subtly.  The atmosphere in reality is not pure and perfect so there is always a certain amount of dust or fog in the air reducing visibility at a distance.  Even if apparently imperceptible, these effects give depth and realism to all scenes.  At the other end of the spectrum, fog can be used to create some dramatic effects when used in conjunction with lighting and lens effects which were previously only achievable in post production.

VrayEnvironmentFog settings are found under the Environment tab of the Environment and Effects window (8 - keyboard shortcut).  We started in this scene by adding a general fog set to 30m height which extends just above the tops of the trees. This is set to 100m fog distance which just gives a subtle depth to the image without making it too foggy as it were.

The fog colour in this case is completely white rather than the 217 default.  GI Scattering is turned off.  Sometimes this can produce a nice effect and is of course more physically accurate but it increases render times massively and can certainly be done without for most scenes. The default subdivs are set to 8 but having played around with these values I usually set them to 300 as it seems to be the optimum value for general fog in an external scene combining detail with speed of rendering.  Some tweaking of this for different scenes may be necessary but 300 seems to be the sweet spot.  In theory this parameter determines the number of points inside the fog at which volumetric light is evaluated meaning lower subdivs should be noisier but quicker to render.  From extensive testing we have found that this is not always the case and that sometimes higher subdivs can actually speed up the render.  Bear in mind that we use the universal method for our render settings so this may be different with different render settings.

In Ray Filter settings the affect shadows and affect GI are both unchecked.  This allows for a greater amount of fog without having to alter your camera settings too much to compensate from the lower light levels as a consequence of the fog.  There appears to be little difference to the overall appearance of the fog in the scene.



The second and third fog effects are used to produce additional fog in specific areas, in this case, more in the trees behind the building and some low fog in the foreground.  A simple box is used as a gizmo in the VrayEnvironmentFog nodes section.  This means that this fog will be confined to the gizmo area.  If using a box as a gizmo make sure it is un-renderable in object properties.

When distributing local areas of fog in a gizmo we quite often add a basic noise map in the density slot to create some unevenness in the fog distribution. This is particularly effective amongst trees or ground cover giving the impression light air movement blowing the fog around.  Step size is important when using maps for colour density of emission.  The sampler used in this instance is known as a raymarching sampler which steps through the volume evaluating volumetric textures and lighting. Generally step size should be two to three times smaller than fog distance to work well.  We typically use half the size a rule of thumb.

Make sure that if you have multiple gizmos that the gizmo merge mode is set to blend otherwise you can get unwanted interactions and noise between them.  Sometimes if the gizmo is complex geometry rather than a simple box you can get these unwanted effects as well.

you can of course also have the VrayEnvironmentFog as a render element under VrayAtmosphere in render elements in case your computer is not powerful enough to render it into the scene or you would rather have a quicker result and comp it in post. 

VrayAtmosphere render element

As mentioned previously lots of different effects can be created using VrayEnvironmentFog.  In the example below of the original Carey House scene a fog gizmo was placed in front of the car head lamps which were made in the same way as the courtyard tree light illustrated in the last tutorial on internal lighting.  Add lens effects of course and there you go, straight out of the frame buffer with no post. 

The next tutorial will be the final one in the Carey House series where we look at render settings and basic post production techniques to produce the final images.

Peter Guthrie SoA Lighting Masterclass

Following on from Guthers' resoundingly successful lighting masterclass at the State of Art Academy last month I thought I'd have a quick round-up of my favourite images from each artist from an architectural perspective. One of the joys of 3d viz is having the ability to recreate reality rapidly and in a consequence free environment in any direction that your imagination takes you.  Phil Hunter once summed it up by saying, "you wouldn't set a dog on fire cos it's not a nice thing to do, but in 3d you can"... It's always interesting to see people's take on famous works of architecture placing well know buildings in different environments or applying different materials, structure etc. It's all the more interesting to see a building which you have designed be put in the hands of 12 highly creative people and given free rein for a week.

Here is a list of my favourite examples and treatments from both a viz and architectural perspective.

Alessandro Consonni

There's a beautiful clarity to Alessandro's aproach which essentially uses many of the original materials but remade to create a slicker cleaner aesthetic.  The portrait aspect ratio of the image is also highly appropriate to illustrate the only vertical space in a scheme which is otherwise dominated by the horizontal.

Alessandro Massi Mauri

Great use of Forest Pack Pro in this one to create the rough desert environment.  There's also an interesting vertical rhythm of the cacti mirroring the rhythm of the building facade.  Following Alessandro's completion of this image Guthers commented on how the landscape was reminiscent of Rick Joy's houses in the deserts of Arizona...

 Rick Joy's Desert Nomad House

 Rick Joy's architecture studio

Alessandro Massi Mauri -  'Rick Joyed' version

...The next thing you know...

Some architect friends of mine would doubtless deride this approach as fatuous, derivative plagiarism devoid of rigor, process and architectural interrogation.  I however think that this is a really interesting example of how with the use of 3d viz, ideas can be tested rapidly and to a certain natural conclusion allowing for a potentially greater degree of architectural design development within the same time frame. 

Darwin Ceballos

The architecture is largely untouched in this example but the landscape is stunning and the composition is great.  Lovely colour balance too. In some ways I feel this landscape is almost more appropriate for the architecture than the original.

George Nijland

I love George's work in general and this is no exception.  Great atmosphere and very skillful use of Forest Pack Pro This is one of the few examples where the landscape has been altered to express the solid concrete base of the building.  George has really managed to capture the essence of the architecture with the lightweight timber 'roofwork' floating atop the solid 'earthwork' base.

This approach to built form is born out of an architectural tectonic described by the great 19th Century German architect and art critic, Gottfried Semper in his seminal book The Four Elements of Architecture  which inspired me as a student.

Giuliano Sabadin

A very interesting ethereal world created by Giuliano strips the building and landscape almost bare of materiality and leaves only the pure architectural form to be read. 

Jeroen Henning

I love the scale of this one.  All modeled I'm lead to believe.  Distant mountains really pushing the spacial limits of the 3ds max environment.

Matthias Arndt

This is a particularly interesting example by Matthias who has expressed the horizontal structural slabs and infilled between in contrast to the original timber veil sailing over the floor slabs creating a solar shading screen across the entire elevation.  Below is an early massing study which was developed during the design development of the Carey House project where this approach was tested.  Looks like Matthias has refined it somewhat. 

An early study during the design development of Carey House

Oguz Kalafat

Two things I like about this one.  Firstly the idea of opening the architecture up to an infinite landscape, namely the sea, and secondly using an actual HDRi moon from PG SKies HDRi 2118 Sky combined with a Phoenix FD sea by Chaos Group.  Apparently a little colour correction had to be done within the HDRi to knock out the warm tones in the moon and prevent it from looking like a dull sun. 

HDRi Moon

HDRi - 2118 Moon get it here

Paolo Faleschini

Paolo Faleschini

I had to include both of these images by Paolo as I couldn't decide.  Both lovely and both express the architecture perfectly.  The second image is especially interesting in the way that the light draws your eye around the the image in a subtle spiral as PG observed.  Very cool. 

Robert Dukes

Architecturally this is my favorite.  Essentially substituting an expensive timber facade which serves little purposes other than solar shading over the glazed areas and replacing it with off the shelf industrial sheet material.  A really imaginative way of value engineering the scheme perhaps whilst maintaining the essence of the architecture.  Love it!  

Sandra Ferminan

Beautiful, minimal, clean. Pawsonesque.

Walter Pegolo

Lovely atmosphere, simple composition and viewed from a position which I hadn't explored before.

For a full gallery of the images created during the Lighting Masterclass see Guthers Blog

If anyone is interested in having a go at recreating the Carey House project we are thinking of running a small competition following the release of the full max scene on The Boundary Store in the next few weeks.  The prize will be The Boundary Scene No.2 and perhaps a cheeky HDRi sky or two.

Carey House Tutorial 07 - Lighting Internal

Having looked previously at the basic environmental lighting set up with HDRi sky domes we are now going to look at some of the internal lighting set up.

Our general approach to all aspects of 3d visualisation is to attempt to recreate natural conditions as closely as possible and internal lighting is no exception i.e light sources are set up as they would be in reality from lamps, spots, pendants etc rather than faking the lighting with fill lights and invisible sources. That said it is never a good idea to be too slavish with this general philosophy if it is reducing the quality of the image. After all, photographers often set up specific lighting to create certain atmospheric effects in their images which may belie the reality of a space.

In this scene we have used Vray plane lights, sphere lights and ies lights sometimes alone and sometimes in combination to create specific effects.

The general plane light set up is pretty simple.  In this case we used Luminous power for the intensity units but we tend to use Radiant Power more these days which is measured in Watts.  It makes no difference to the light output but can make a big difference to the unit values making it slightly easier to manage e.g 350000 lm = 500 w (approx).  

It's usually easier to use temperature for general internal lighting rather than colour unless you are aiming for some specific coloured lighting effects.  The internal lighting in this scene ranges from 3000 kelvin to 4500.  It's always worth adding a bit of variation to internal light temperature depending on the type of light source.  A kitchen pendant light is likely to be significantly warmer than a fluorescent strip light under the cupboards.  The plane lights are generally only made visible if a lens effect is required produced from the intensity of the source, see below. Subdivs are left at the default 32.  Shadow bias and Cutoff are also left at the default values in this case. Sometimes these values can be very important to speed up render times if there are hundreds of lights in a scene and many of them, particularly in the distance, need only affect their immediate surroundings rather then the entire scene.

Lens effects were introduced in VRay 3.0 and we tend to use them in most of our scenes.  A lot of people still prefer to add lens effects in post but in our quest to reduce post to minimum this provides a really simple and effective alternative.  The Vray lens effects control glare bloom and diffraction of light sources.  The general rule of thumb is that the greater the intensity of light source the greater the lens effect as in reality.

Bloom and glare work independently although I often use glare alone as bloom can soften an image too much.  Depending on the intensity of your light source you may need to play around with the Weight and Size sliders.  I generally find that glare works best with these two parameters set at a fairly similar value or if anything the size slightly greater than the weight. Increasing the weight above the size can result in a slightly strange cut off effect but each light source requires tweaking differently. 

Bloom is controlled with weight, size and shape but in my experience needs to be used with great subtlety as the glare effects, if used correctly, can do much of the work which the bloom is doing.  

Diffraction in Vray lens effects can produce some nice chromatic aberration effects but can easily be turned off interactively without the need to re-render.  All these examples are of course exaggerated for clarity. 

Diffraction on

Diffraction off

The lighting of the tree in the court yard was created using a combination of a sphere light and an ies spotlight. The sphere light is used to create a general glow around the light source and the is spot is used to create a more directional flood light up the tree.

Make sure if using two light sources in conjunction like this that they are not intersecting.  The sphere light is set to visible so as to create the lens effects therefore the ies (which has an invisible source) must be positioned just in front of the sphere so as not to be obscured by the sphere.

lens effects not only work for internal lighting of course and sometimes they can really add a nice finishing touch to an HDRI.   Below is an example of HDRI 1853 shining straight into the camera through the trees with glare set to fairly low values.

In the next tutorial we will have a look at how VrayEnvironmentFog is used in the scene to create depth and atmosphere.

Carey House Tutorial 06 - Lighting

Now we come to the fun bit, lighting and rendering.  HDRi lighting forms the basic environmental lighting setup for all of our scenes.  Many of you will already use Peter Guthrie's excellent HDRi skies, available here, which are in my opinion the best skies available (but then I would say that) and no doubt you have followed Peter's instructions regarding their use for best results.  I think, however, it is worth going over again here to illustrate some of the project specific settings and some of the immense variation we were able to achieve with only a single sky!

Hdri 1853 horizontal rotation 80 degrees

Hdri 1853 horizontal rotation 110 degrees

Hdri 1853 horizontal rotation 200 degrees

We start by loading a sky into a Vray HDRI map and renaming the map to correspond to the number of the sky.  Make sure the mapping type is set to spherical.  PG Skies, which we use exclusively, usually work with processing multipliers set to 1.0.  Sometimes it can be useful to set the Overall multiplier to 0.1 and the Render multiplier to 10 giving exactly the same output but allowing the HDRI map to be visible in the material editor.  You can of course adjust these values to increase or reduce the intensity of the sky.  I usually use the Vray physical camera parameters to adjust light levels but adjusting the HDRI can be useful if for example you have a scene set up with lots of artificial interior lighting and you change the HDRI sky with a different light intensity, it is often quicker and easier to adjust the HDRI rather than all of the internal lights.

Set the Colour space Type to Inverse Gamma.  The default value is 1.0.  Lower values give greater contrast and higher values give a more washed out result.  Most PG Skies work best with gamma set between 0.7 - 0.85 with the sweet spot often being around 0.75.  More on Gamma settings below.

Next set up a Vray Dome Light and give it a name corresponding to the the HDRI.  Set the intensity units to Image which is the default and make sure the multiplier is set to 1.0.  The Multiplier can be used to adjust the intensity of the HDRI map but if using a Vray physical camera it is generally more accurate to leave this at 1.0. 

Finally instance the HDRI map into the texture slot of the Dome light and lock to dome orientation. 

Horizontal rotation of the sky i.e. where the sun is coming from is controlled in two ways; either in the horizontal rotation dialogue in the mapping section of the HDRI map which works in degrees or by rotating the dome light itself.  I usually rotate the map rather than the dome light through habit.  0.0 rotation equates to East in the HDRI map as in the sun position is due East at 0.0 rotation rather than North as you may expect.  Therefore when thinking of the rotation as points on a compass I usually think of a compass rotated by 90 degs clockwise.  If using the rotate Dome Light method, remember to  check 'lock to dome orientation' in the texture section of the dome light. In the example below we have drawn a simple triangle linked to the dome light pointing in the direction in which the sun is shining so as you rotate the dome light you have a quick visual reference.  Apparently this is something which may be added to Vray dome lights in future releases.

PG Skies are of a sufficient resolution (particularly the new super hi-res releases such as the excellent new 1714) that we almost always keep the rendered sky in the final image.  If however you wish to replace the sky with a back plate for crazy resolution images (10k plus) you will need an alpha chanel.  Using an HDRI mapped onto a dome light will give you an alpha channel, provided you untick 'affect alpha' in the Dome Light options. 

Alpha chanel

I tend to start by loading in several HDRI skies and assigning them to different dome lights each named occording to the sky number.  I can then easily switch between skies using the Vray Light Lister and test multiple lighting setups quickly and easily. 

Vray Light Lister

Once all of the dome lights are set I like to start by isolating the building and the ground plane so that I can test different lighting setups quickly without having to wait for any complex geometry to upload or light cache to build.  You can also do this with Vray RT if you have a decent graphics card although I generally prefer to do simple 1200px renders using the progressive image sampler and save them out in the frame buffer history.

HDRI 1847 rotated between 0-360 degrees

In the example above a simple grey override material with a VrayEdgesTex is used to increase the speed of the render further as it is the sky and general lighting which is being tested. These are 1200 x 800px renders, progressive 50 passes approx which took about 30 seconds each.

As previously mentioned the gamma settings in the HDRI map can be adjusted to achieve differing results.  Below are some examples of a moody sky 1853 which is one of my favorites on account of the broad range of results which can be obtained with different horizontal rotations.

Lower gamma values not only produce more contrast but also appear brighter which may require camera exposure adjustments.  There also seems to be a correlation between lower gamma valuse and increased noise resulting in longer render times.  I'm not sure what the technical reason is for this but I often find that if a scene is rendeing slowly at Gamma 0.7, increasing it to 0.75 can make a big difference in speeding it up. 

If a higher gamma value is used but more contrast is required we often use a simple 'S curve' in the Vray Frame buffer.  This is particularly necessary when using our standard colour mapping settings of gamma 2.2 with a burn value of 0.05. 

Vray Frame Buffer with no curve

Vray Frame Buffer with subtle 'S curve' to increase contrast

Colour mapping settings

It's always worth testing each sky you load in to a scene with different rotations and different gamma settings as you often find drastically different moods can be created with a single sky. 

HDRI 1853 with various rotations and gamma settings

In the next tutorial we'll have a look at some of the artificial internal light settings and the excellent Vray lens effects.

Carey House Tutorial 05 - Pool

Water is always a tricky thing to get right but also enjoyable to develop as it can really bring a scene to life.  In the Carey House there is only one small area of water, visible in only one or two views but I think it's worth dedicating a tutorial to as it may provide useful tips for many situations.

There are three basic steps to create this shallow reflecting pond.  
1. The water texture
2. The wet edge
3. The pebbles

There are many way to produce water in 3d.  And different techniques suite different environments.  We have used bump, displacement, 3d vector based displacement (Chaosgroup's Phoenix and similar), simulation, particles etc...for different applications.  In this instance however we have simply used bump to reduce render times and simplify geometry.  It also means that when we make this scene available for purchase, no additional plugins will be required for the water. 

The basic material is similar to glass but with a reflection glossiness of 0.8 and a Fresnel IOR of 1.6 rather than 1.8. The refractive IOR is 1.33 for water generally giving the impression of the pool becoming shallower as the angle of incidence of the camera increases.  Two noise maps of differing sizes are comped together with a large noise map masking between them.  Note that in this case we wanted the ripples to look like they were slightly running across the pool as if a gentle breeze may be blowing from one end. This is achieved by adjusting the x and y tiling coordinates in the noise map parameters effectively stretching map. 'y' is approximately five times 'x' in this example.

The wet edge of the concrete pool was made with a blend material to give the impression of water having splashed up out of the pool. The basic dry concrete material was copied and made almost entirely reflective by deleting the reflection and reflection glossiness maps and simply applying a light colour to the reflection channel (approx 210). A painted black and white bitmap is used to blend the two materials.  The stepping stones along side the pool are textured in the same way but with a noise map used to blend the two materials. 

To add another level of detail the bottom of the pool is filled with pebbles.  Firstly a gravel base was created with a VrayDisplacementMod as in the driveway tutorial.  The large pebbles which were scattered with Forest Pack Pro amongst the grass in the first Carey House tutorial are used to full the pool.

The Forest Pack settings are similar to those previously described for the gravel drive.  Two points to mention are boundary checking which is set to size to prevent scattered objects from extending past the surface upon which they are scattered and collisions.  In this case collisions are not enabled as it was not necessary due to the fact that the pebbles are obscured by reflection and refraction beneath the water and it was easier to achieve the desired density without enabling collisions.

Forest Pack Pro dialogue

The final scene was a dusk shot with a strip light illuminating the pebbles which is why we went for scattered geometry rather than displaced.  Quite a nice but relatively simple effect.

In the next tutorial we will have a closer look at HDRI lighting of the scene and see what can be achieved with the peerless PG Skies.