This tutorial concerns itself with composting 3d elements into a still photograph. This is an effective technique that can help with visualization, for example adding or replacing existing structure with proposed architectural designs. There are many uses for this technique, please feel free to explore them. It is not an application specific method, it can be used with any 3d package, although in this instance I am using 3DS Max.

We will begin with an initial image. There are many things to consider when it comes to selecting the proper photograph/image to use. In this tutorial, I will assume you have no knowledge of the focal length of the camera, height of the person taking the picture etc. Try to use a photograph that has as little warping as possible (fisheye etc.) as this will complicate things greatly.

 

Initial Image

 

The first thing we need to determine is the horizon line. Then we determine the vanishing points. This will help us set up a grid that we can align our viewport ground plane to.

The next few steps are done in Adobe Photoshop. If you need a primer in perspective, horizon lines and such, check here.

 

In order to find our horizon line, we simply intersect two pairs of lines on either side of the image that follow existing perspective lines. Now create a line that connects our two intersection points. This will be our horizon line. Due to human error, sometimes the line is not perfectly horizontal because the camera was at a slight angle when the picture was taken. When you draw the line in photoshop, pay attention to the angle (located in the info dialog) and rotate your image accordingly. (See below)

 

 

Secondly I create an array of lines emanating from the endpoints so as to create a grid defining the ground plane. This will be the grid that we compare to our viewport grid. It is important to be as precise as possible in this step, making sure you stay true to the endpoints.

Now that our image is prepared, we can insert it into the background of our camera viewport.

- Create your target camera perpendicular to our image plane.

- Make the cameras horizon line visible.

- Select both the camera and the target.

- Move them vertically either up or down in order to match the images horizon line.

Make sure your viewport grid is visible. The viewport grid will represent the ground plane. You may change your grid color so the relationship between the viewport grid and the reference image grid is clearly visible.