During our work we came across the problem of modelling the environment of a real estate development many times.
Modeling slopes and uneven terrains is a challenging quest.
We have worked out a couple of methods how to make this right. First, let me tell you that we are not really aware of how to make this using NURBS. We usually stick to polygons, as is it a flexible and well-developed tool in max. The major disadvantage of editable polygons is the lack of history. You can’t really go back 50 steps – forget about a chamfer and see the end result without it.
So try to create clones of your objects and name them appropriately.
This tutorial covers the method of creating an aslope terrain with three streets crossing each other on it.
This modeling technique was largely used to create the terrain for the Buda Castle.
Create or redraw the outlines of the streets so that they form a closed spline. If you have a CAD drawing then make sure you delete all the unnecessary elements and get a clean closed result like on the image below.
Create a low-poly object that will server as a proxy for your terrain. You can create this by slicing, by cutting or by simply copying edges. The areas beneath the spline should cover the fillets at the crossing.
Make sure all the polygons inside the editable polygon object remain quads. Try to avoid triangles or pentagons etc.
Make a google search if you aren’t sure how to do this step.
Move the edges of the proxy object along the Z axis to the desired level.
Make sure you Z-scale the edges highlighted on the image below to zero, so that the streets tilt only in one direction.
Optionally: You can set edge chamfers at dense or steep locations, where street topology would be lost in the next step.
Apply a Turbosmooth modifier to your proxy object. For more control use meshsmooth. This lets you set edge-crease and edge-weight for edges individually thus giving greater control over the end result.
Create a copy of your street lines. This will be used later for selecting certain polygons of your final object. Now we have to carve the lines of the streets into the terrain model. This can be done with various tools: shapemerge might give odd results, as does boolean. The insert shape modifier is a nice plugin, but unfortunately it is not free. What we do now – and works almost in every case – is ProBoolean.
Extrude the original lines so that it completely overlaps your proxy terrain object, then apply proboolean with the following settings:
Apply a “Turn to Poly” modifier before going on.
Next step is selecting the polygons of the street. For this we use a small trick. Get the copied street-lines object and apply a small offset to the splines. If you have more spline elements in one object make sure they are oriented in the same direction (all CW or all CCW).
Delete the original spline element and set an extrude on top of the stack. As an end result you have an object that is slightly bigger than the original one.
Apply a “volume select” modifier to your terrain and use the previously created object to select your street-polys.
At this part of the modelling process it’s usually OK to give another material ID to the selected elements.
As you might probably have seen this technique is only useful if you want to distinguish between two different surfaces like grass and pavement. We have worked out another method that is suited for any number of different surfaces.
Stay tuned for more tutorials.