Section 4.1.2
Adding Standard Include Files

Using our personal favorite text editor, we create a file called demo.pov. We then type in the following text. The input is case sensitive, so we have to be sure to get capital and lowercase letters correct.

#include "" // The include files contain #include "" // pre-defined scene elements #include "" #include "" #include "" #include "" #include ""

The first include statement reads in definitions for various useful colors. The second include statement reads in some useful shapes. The next read pre-defined finishes, glass, metal, stone and wood textures. It is a good idea to have a look through them to see but a few of the many possible shapes and textures available.

We should only include files we really need in our scene. Some of the include files coming with POV-Ray are quite large and we should better save the parsing time and memory if we don't need them. In the following examples we will only use the, and include files so we will better remove the appropriate lines from our scene file.

We may have as many include files as needed in a scene file. Include files may themselves contain include files, but we are limited to declaring includes nested only ten levels deep.

Filenames specified in the include statements will be searched for in the current directory first and, if not found, will then be searched for in directories specified by any +L or Library_Path options active. This would facilitate keeping all our "include" (.inc) files such as, and in an "include" subdirectory, and giving an +L switch on the command line to where our library of include files are.

Section 4.1.3
Adding a Camera

The camera declaration describes where and how the camera sees the scene. It gives x-, y- and z-coordinates to indicate the position of the camera and what part of the scene it is pointing at. We describe the coordinates using a three-part vector. A vector is specified by putting three numeric values between a pair of angle brackets and separating the values with commas.

We add the following camera statement to the scene.

camera { location <0, 2, -3> look_at <0, 1, 2> }

Briefly, location <0,2,-3> places the camera up two units and back three units from the center of the ray-tracing universe which is at <0,0,0>. By default +z is into the screen and -z is back out of the screen.

Also look_at <0,1,2> rotates the camera to point at the coordinates <0,1,2>. A point 5 units in front of and 1 unit lower than the camera. The look_at point should be the center of attention of our image.

Section 4.1.4
Describing an Object

Now that the camera is set up to record the scene, let's place a yellow sphere into the scene. We add the following to our scene file:

sphere { <0, 1, 2>, 2 texture { pigment { color Yellow } } }

The first vector specifies the center of the sphere. In this example the x coordinate is zero so it is centered left and right. It is also at y=1 or one unit up from the origin. The z coordinate is 2 which is five units in front of the camera, which is at z=-3. After the center vector is a comma followed by the radius which in this case is two units. Since the radius is half the width of a sphere, the sphere is four units wide.

Section 4.1.5
Adding Texture to an Object

After we have defined the location and size of the sphere, we need to describe the appearance of the surface. The texture block specifies these parameters. Texture blocks describe the color, bumpiness and finish properties of an object. In this example we will specify the color only. This is the minimum we must do. All other texture options except color will use default values.

The color we define is the way we want an object to look if fully illuminated. If we were painting a picture of a sphere we would use dark shades of a color to indicate the shadowed side and bright shades on the illuminated side. However ray-tracing takes care of that. We pick the basic color inherent in the object and POV-Ray brightens or darkens it depending on the lighting in the scene. Because we are defining the basic color the object actually has rather than how it looks the parameter is called pigment.

Many types of color patterns are available for use in a pigment statement. The keyword color specifies that the whole object is to be one solid color rather than some pattern of colors. We can use one of the color identifiers previously defined in the standard include file

If no standard color is available for our needs, we may define our own color by using the color keyword followed by red, green and blue keywords specifying the amount of red, green and blue to be mixed. For example a nice shade of pink can be specified by:

color red 1.0 green 0.8 blue 0.8

The values after each keyword should be in the range from 0.0 to 1.0. Any of the three components not specified will default to 0. A shortcut notation may also be used. The following produces the same shade of pink:

color rgb <1.0, 0.8, 0.8>

Colors are explained in more detail in section "Specifying Colors".

Section 4.1.6
Defining a Light Source

One more detail is needed for our scene. We need a light source. Until we create one, there is no light in this virtual world. Thus we add the line

light_source { <2, 4, -3> color White}

to the scene file to get our first complete POV-Ray scene file as shown below.

#include "" background { color Cyan } camera { location <0, 2, -3> look_at <0, 1, 2> } sphere { <0, 1, 2>, 2 texture { pigment { color Yellow } } } light_source { <2, 4, -3> color White}

The vector in the light_source statement specifies the location of the light as two units to our right, four units above the origin and three units back from the origin. The light source is invisible, it only casts light, so no texture is needed.

That's it! We close the file and render a small picture of it using the command

  povray +w160 +h120 +p +x +d0 -v -idemo.pov

If our computer does not use the command line, we have to read the platform specific docs for the correct command to render the scene.

We may also set any other command line options we like. The scene is written to the image file demo.tga (or some suffix other than .tga if our computer uses a different default file format).

The scene we just traced isn't quite state of the art but we will have to start with the basics before we soon get to much more fascinating features and scenes.

Section 4.2
Using the Camera

Section 4.2.1
Using Focal Blur

Let's construct a simple scene to illustrate the use of focal blur. For this example we will use a pink sphere, a green box and a blue cylinder with the sphere placed in the foreground, the box in the center and the cylinder in the background. A checkered floor for perspective and a couple of light sources will complete the scene.

We create a new file called focaldem.pov and enter the following text

#include "" #include "" #include "" #version 3.0 global_settings { assumed_gamma 2.2 // for most PC monitors max_trace_level 5 } sphere { <1, 0, -6>, 0.5 finish { ambient 0.1 diffuse 0.6 } pigment { NeonPink } } box { <-1, -1, -1>, < 1, 1, 1> rotate <0, -20, 0> finish { ambient 0.1 diffuse 0.6 } pigment { Green } } cylinder { <-6, 6, 30>, <-6, -1, 30>, 3 finish { ambient 0.1 diffuse 0.6 } pigment {NeonBlue} } plane { y, -1.0 pigment { checker color Gray65 color Gray30 } } light_source { <5, 30, -30> color White } light_source { <-5, 30, -30> color White }

Now we can proceed to place our focal blur camera to an appropriate viewing position. Straight back from our three objects will yield a nice view. Adjusting the focal point will move the point of focus anywhere in the scene. We just add the following lines to the file:

camera { location <0.0, 1.0, -10.0> look_at <0.0, 1.0, 0.0> // focal_point <-6, 1, 30> // blue cylinder in focus // focal_point < 0, 1, 0> // green box in focus focal_point < 1, 1, -6> // pink sphere in focus aperture 0.4 // a nice compromise // aperture 0.05 // almost everything is in focus // aperture 1.5 // much blurring // blur_samples 4 // fewer samples, faster to render blur_samples 20 // more samples, higher quality image }

The focal point is simply the point at which the focus of the camera is at its sharpest. We position this point in our scene and assign a value to the aperture to adjust how close or how far away we want the focal blur to occur from the focused area.

The aperture setting can be considered an area of focus. Opening up the aperture has the effect of making the area of focus smaller while giving the aperture a smaller value makes the area of focus larger. This is how we control where focal blur begins to occur around the focal point.

The blur samples setting determines how many rays are used to sample each pixel. Basically, the more rays that are used the higher the quality of the resultant image, but consequently the longer it takes to render. Each scene is different so we have to experiment. This tutorial has examples of 4 and 20 samples but we can use more for high resolution images. We should not use more samples than is necessary to achieve the desired quality - more samples take more time to render. The confidence and variance settings are covered in section "Focal Blur".

We experiment with the focal point, aperture, and blur sample settings. The scene has lines with other values that we can try by commenting out the default line with double slash marks and un-commenting the line we wish to try out. We make only one change at a time to see the effect on the scene.

Two final points when tracing a scene using a focal blur camera. We needn't specify anti-aliasing (the \Clo{+A} switch) because the focal blur code uses its one sampling method that automatically takes care of anti-aliasing. Focal blur can only be used with the perspective camera.

Next Section
Table Of Contents