Maxwell Render V1.7.1 Simple materials tutorial - Tim Ellis
Quick links in this document, click below to jump to that section:-
1:- AGS clear glass - using the material wizard.
1a:- AGS tinted glass - modifying clear AGS.
1b:- AGS opaque glass - modifying tinted AGS.
2:- Stone basics - Using real scale texture maps.
1:- AGS - clear & tinted
The only reason AGS (Architectural Glass Solution) was created, was because of Maxwell's limitations for sunlight passing through glass.This is the work around which removes any refraction, retains controlled reflections and allows sunlight to pass through a glass object as expected.
Create a new MXM by right clicking the material list in Maxwell Studio.
Confirm creation & name accordingly. AGS in this case.
Next use the Wizard to create the base AGS material.
Confirm 'White' for clear AGS glass.
Cityscape standard AGS uses 20% reflectivity. Enter 20 & confirm.
The Refractive Layer is counter representitive as there isn't any refraction. A more correct term would be 'Transparency Layer'. The reflective layer, is set to 20% as per set in the wizard.
* Note - The refractive layer must have an Index of Refraction (ND) = to 1.000 and must have a transmittance colour of pure white, 255,255,255. (Hi-lighted in gold below.)
The material will fail to give correct results if either of these are set incorrectly. Don't worry the wizard will automatically set these values for you.
By default the reflective layer Reflectance 0' colour is grey (left hand side of image below), we set this to pure white for clearer reflections (right hand side of image below).
You can see in the preview window the difference this colour change makes to the reflections.
That is a standard AGS material. For controlled % of reflections, increase or decrease the % of the reflective BSDF layer.
1a:- AGS tinted glass - modifying clear AGS.
Firstly we need to add a tint BSDF Layer to our AGS material. Right click the Layer stack and 'Add BSDF'.
Change the Reflectance 0' colour to white, or the colour of your choice. White & blue in examples below.
Un-check the Roughness = 100 box to switch the layer to 99. (Lambertian.)
* Note - Wizard created tinted AGS will apply 0% roughness (100% reflective) to the tint layer - Tint layers will have more effect with a high roughness / very low reflectivity setting.
This method will also retain the control over the materials reflectivity, as it will be controlled by % of the Reflective Layer only.
These settings will usually suffice for a standard tinted AGS material. The strength of the tint can be adjusted using the % of the tint layer combined with the % of the Refractive layer..
1b:- AGS opaque glass - modifying tinted AGS.
We can use the tinted AGS as a base for opaque AGS glass. We conrol this by the % of the Refractive Layer in the material.
Here the Refractive layer is lowered to 10% - ie 10% transparency or 90% opacity.
If a frosted AGS with lower reflectivity is required, then adjust the Refractive & Reflective layers %'s to suit. Reduce the Reflective layer to 0% if no reflections are required.
Example below shows 5% reflectivity for a 90% opaque white tinted AGS and 10% reflectivity for a 50% opaque blue tinted AGS.
2:- Stone basics - using real scale texture maps with normalized UV projectors.
Maxwell has a handy function in it's UV projectors. The 'Cube' projector can be applied to any object and 'Normalized'.
This 'Normalize' function, will tile a texture as per it's set dimensions, automatically across the area of an object.
So using a texture map of 0.5m x 0.5m, Maxwell will automatically tile the texture ten times for an object 5m x 5m in size.
Create a new MXM by right clicking the material list in Maxwell Studio.
Confirm creation & name accordingly. Stone in this case.
We'll use textures already created, in this case this Yorkshire stone from the Make Birmingham project.
Load the colour map into the Reflectance 0' texture channel.
Next we need to tell Maxwell what dimensions the texture map has. This particular map has 5 slabs across the X axis and 8 slabs along the Y axis.
Let's use a single slab dimension of 900mm x 600mm with a 10mm grout line.
0.9 meters x 5 slabs + (5 x 0.01 meter grout) = 4.55meters wide. -> 0.6 meters x 8 slabs + (0.01 meter grout x 8) = 4.88meters long.
Turn on the Real scale button in the texture window and enter the above dimensions for Tile X and Tile Y.
Drag and drop this texture from the Reflectance 0' channel to the Reflectance 90' channel. This will keep the settings already applied in the texture tiling section and will save you having to set them all individually.
Adjust the brightness of this channel to +10 and saturation to -10, which will help keep the colour of the map at high glancing angles, instead of a pure white colour being used.
Uncheck the 'Lambertian' button to change the roughness from 100 to 99. This allows more specular movement across the material, than a pure 100% Lambertian surface does.
Next, drag and drop the texture from the Reflectance 0' channel, this time to the Bump channel and set the value to 100. Activate the Normal map button as we'll be using a Normal map for the bump effects.
Click the texture map icon for the bump channel and select the Normal map.
So now we have our base colour layer with the correct real scale applied and correct image maps in place.
Now we need to add a specular layer to the material. Right click the Layers stack and choose 'Add BSDF'.
Adjust the weight % of each layer, 80 / 20 or 70 / 30 are good starting points for Stone.
Select the second (specular) BSDF Layer in the stack and load the relevant maps, making sure the real scale values are set correctly and the real scale button is pressed.
You will notice I haven't loaded the colour map into the Reflectance 0' for the specular layer, but have loaded the Bump map. This is to aid with variation across the material.
If a different variation map is used, set the real scale values accordingly for that variation map. (See Variation map tutorial - Click here to view tutorial.)
You can adjust the reflectivity of this material by adjusting the Brightness & Contrast sliders in the texture picker, in conjunction with lowering the maximum of the roughness value - set to 99 in the example below, using the default values for the specular map.
This example below uses lower Brightness levels and higher Contrast levels for the texture.
This example below uses the same texture settings but a lower maximum for the roughness value.
* Note - Maxwell uses the whitest point of a specular texture map as the maximum value set in the roughness channel. It uses the blackest point in the specular map as the lowest value - zero which equates to 0% roughness & maximum reflectivity.
Lets add a layer for the grout / mortar, so we can make it more pronounced, or change the colour if neccesary. I've made this particular 'weight map' (clip map) using the mortar selection method as described in the Brick tutorial. (Click here to jump to that tutorial.)
Right click the BSDF Layer stack and 'Add BSDF' as previously.This time we need to load the weight map instead of using the % weight as set for the two BSDFs previously. White allows the BSDF layer to be visible, black to be invisible, as per normal use of a clip map.
Now we set the colour of the grout as required, set the Roughness value to 99% and load the normal map into the bump slot as per the previous layers.
Comparison of the two material versions. The left hand material doesn't have the extra grout layer, whereas the right hand side material does.
Using the same method as the additional grout layer above, we can use another texture to add more variation.
Here I've used a modified version of the bump map we used for the specular layer variation, as a weight map for the BSDF layer.
I've also lowered the saturation and brightness for the Reflectance 0' & 90' colour maps, whilst the Specular map & Normal map are as previous.
Tim Ellis 2010 - tim.ellis@emp3d.com