Creating a Simple Terrain in 3DS Max - Part 2: Creating the Material

In part one of this tutorial, we created a simple terrain using a height map. In this part, we will create a material that changes depending on the height of the terrain.

The material we will use creates a blend of 2 existing materials found in the 3dsmax material library, although it could be used to blend any materials.

Open your terrain scene from part 1 of the tutorial and load the 3dsmax material library. In the material editor create a blend material by clicking get material and start typing the word blend in the browser.

The blend material has 3 basic settings; 2 materials and a mask that creates the blend.

Apply the Ground_Grass to the material 1 slot and Ground_Grey_Dirt2 to the material 2 slot by dragging them from the browser onto the map buttons.

Apply the height map to the mask slot by clicking the button, selecting bitmap and navigating to your height map image.

Apply the blend material to your terrain and render the scene.

The terrain should now have grassy textures at the base and rocky textures higher up. You may notice that the textures are far too big for the terrain, so we need to modify the grass and dirt materials.

Depending on your height map, you may find that you have too much rock and not enough grass (or the other way around). You change the balance of the blend by activating the mixing curve and changing the settings. Try different settings until you are happy with the results.

In the blend material, click on the material 1 map button (Ground_Grass), then click on the diffuse map button for the grass material.

In the coordinates box, change the tiling settings to 5 x 5 and render the scene.

You will notice that the grass texture is now much smaller. You may also notice a repeating pattern in the grass.

Try changing the tiling settings to get a result you are happy with (remember that the tiling pattern is only really noticeable when viewed from a distance). I settled on 3 x 3, but yours may vary.

Once you are happy with the settings, try the same techniques to modify the dirt texture.

Creating a Simple Terrain in 3DS Max - Part 1: Creating the terrain

The following technique uses a height map to tell 3DS Max which parts of the object are higher than the others.

A height map is a black and white image where black is the lowest part of the map and white is the highest.

To create the height map, open Photoshop and make a new image at 1024x x 1024 pixels (File > New... or Ctrl + N).

Fill the background with black and create a new layer (Layer > New > Layer... or Ctrl + Shift + N).

The new layer will contain the information for our height map. It is tempting to try and paint your terrain manually, but this will usually look too synthetic and have sharp edges (think of Mario 64). To make our landscape look random, we are going to use the clouds filter.

Make sure your foreground is set to white and your background to black, then apply the clouds filter (Filter > Render > Clouds).

As you will see the filter produces totally random results. Try re-applying the filter a few times to see the variations it can make.

Save your image as a JPEG file (3DS Max will recognize PSD files, but they are usually quite big).

Open 3DS Max and create a plane in the top view (Create > Standard Primitives > Plane). Set the length and width to 100 and the segments to 50 x 50.

In the viewport, turn edged faces on to see the individual polys that have been created.

This will give us enough geometry to create some detail without over burdening the system (this type of map can be quite processor-intensive).

The more segments the plane has, the more retailed the terrain will be. We may need to increase this later, but avoid the temptation to use too many segments as this is likely to crash the system.

Next, we will apply a displace modifier to the plane (Modifiers > Parametric Deformers > Displace)

You will not notice any immediate change to the shape of the plane because we've not told the software what shape the displacement will be or the strength of the displacement.

The shape of the displacement will come from the height map we created earlier.. To apply it, click on the Map button in the Image section of the modifier's properties. Select Bitmap from the list of maps and navigate to where you saved your height map.

Again, you will not see a difference in the shape of the plane because we have not set the strength of the modifier.

Change the strength to 10 in the modifier properties (just above where you set the map). Your plane should now start to resemble a section of terrain.

Try changing the strength to see how it effects the terrain. Try to avoid extremes as it will start to look unnatural (unless you are trying to make the surface of the asteroid in the film Armageddon).

Now we have a terrain that has realistically random bumps, but the edges stop abruptly and spoil the scene. To edit the shape of the terrain, all we need to do is edit the image.

Open the height map image in Photoshop and select a very large soft brush (I am using 300px wide, 0% hardness). Use the brush to paint a rough black edge on the image.

Save the image and go back to 3DS Max. If you have saved over your original height map using the same file name, you should see that the scene has updated to reflect the changes.

If not, reapply the map by clicking in the map button of the displace modifier properties.

Try rendering the scene. You should have a realistic terrain which can be easily modified by editing the image map.

If the terrain looks a little blocky, you could try changing the segments of the plane (but try not to overdo it).

Culling Methods

In normal usage, the word cull means to eliminate things that are unwanted (e.g. the UK government recently initiated a badger cull because of fears that they may spread diseases to cattle). In the realm of computer graphics, culling refers to removing unwanted elements from the render queue.

Rendering is the action of turning the information from an application, such as a modelling programme or game engine, into an image or video.

Depending on the complexity of the scene, rendering can be a very complicated procedure; For example, an average frame in Pixar's Toy Story 3 took over 7 hours to render (bear in mind that Pixar would be using state of the art technology). Therefore, anything that can be done to reduce render times is very important.

View Frustum Culling

View Frustum culling projects a volume denoting the camera's field of view (FOV), usually a cone shape. It checks to see if entire objects are outside the FOV, they are removed from the render queue.

This method of culling is very effective; in the following scene from Grand Theft Auto IV (Rockstar 2013), many on the objects in the map are likely to be culled by the view frustum technique.

Given the size of the map in this game, rendering everything would reduce the frame rate to unplayable levels or, more probably, cause the game to crash.
It is worth noting that view frustum culling is applied on a "per-object" basis, meaning that even a small part of the object is inside the FOV the entire object will still be added to the render queue.

Backface Culling

Backface culling examines the individual faces or polygons of each object. If the face is facing away from the camera, the face is culled from the render queue. Backface culling can result in a significant reduction in rendering as it generally reduces the number of face by 50% (assuming that the object is symmetrical).

Creating Images for Print and for the Web

When creating or looking for digital images, it is very important to know how the image is going to be used. If an image is going to be displayed on a website, it is generally going to be shown at 72 pixels per inch (ppi). But if the image is going to be used in print media, the typical resolution is 300 dots per inch (dpi)*.

The means that image that 360 pixels wide will be 5 inches wide on a web page, but will only be 1.2 inches wide when added to a print document.

A 360 pixel image added to a 10 inch canvas @ 72ppi takes up approximately 25% of the canvas

The same image added to a 10 inch canvas @ 300dpi appears much smaller

Although the image is the same size (360 x 360 pixels) the resolution of the canvas has an obvious effect on the image. If we were to scale the image up, it would become pixelated and this would look unprofessional.

Therefore, we need to ensure that we work with the correct sized images from the outset and bear in mind that if the image is to be used in print media, we will need much higher resolution images.

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*When describing screen density, we use pixels per inch (ppi). and when measuring print density we use dots per inch (dpi). However the terms are often interchangeable and may be used to refer to both. Although it is possible to measure density in pixels or dots per centimetre, the industry standard is inches. 

Anatomy of a 3D Object

Fig 1: The basic elements of a 3D object

When editing an object in 3D software, there are 3 main elements we can alter; vertexes, edges and polygons.

The vertexes are the most basic elements and can be found on the corners of an object.

The edges are lines that connect the vertexes.

If an area is enclosed by edges and filled in, this forms a polygon (sometime known as a face).

When we edit any of the elements of an object, we will usually affect the surrounding elements as well.

In the following example I have moved one vertex on a cube. By doing this, I have altered the surrounding edges and faces connected to that vertex.

Fig 2: The cube before editing

Fig 3: The cube after editing

Using simple changes to these 3 basic elements, we can change the primitives into something totally unique.

Basic Principles of 3D

2D images are defined as having height and width. In digital images the width of an image is defined by the "x" axis and the height by the "y" axis.

When describing image resolution we always state the width followed by the height. For example a high definition TV screen would be 1920 x 1080px.







In the early days of video games nearly all games were exclusively 2D.

This was mainly due to the limitations of the available hardware.

3D images have height, width and depth. The depth information is defined by the "z" axis.


Early 3D images were quite primitive, with little detail and no shading. As the technology improved, 3D graphics became more advanced.

Today 3D images can be seen in many forms from big budget movies such as Avatar and Toy Story to television adverts for products such as toilet duck. 





 Video games have also progressed to the point where the majority of big budget titles feature 3D graphics.

The next big development in 3D graphics is likely to be the use of glasses to produce stereoscopic 3D images.

Rasters Vs Vectors

Raster images are made of a series of pixels arranged into a grid. Each pixel has colour and brightness information.

Photoshop logo JPEG and zoomed in section showing individual pixels

Raster images can display a wide range of colours and are ideal for photographic images. However when a raster image is enlarged the pixels become bigger and more obvious. This causes edges to become jagged, especially curves.

Vector images are created using sets of co-ordinates joined by lines. This means that the image can be enlarged by moving the points without affecting the quality of the line

Cartoon created in Adobe Illustrator and zoomed in section at 2400%, the line is still sharp

Vector images are very useful for creating line art such as the above cartoon and for logos and icons. However, they are limited when trying to display graduated shades of colour.

 Sunset image as a jpeg compared to a vectorised version created in Illustrator

For more information on vectors and rasters, have a look at this video from vector.tutsplus.com.