Range Of Interest - Philips DirectX Visualizer User Manual

Directx visualizer

Table of Contents

3D Solutions

black

These colors can be used to easily determine a value of FarNearRatio for an approximately correct

perspective representation. To do this first get the application to display a flat surface that extends

away from the viewer towards the horizon (such as the floor or a wall in a long hallway). The correct

perspective is achieved if the colored lines on such a surface in the depth map are equidistant on the

screen (see Figure 5). If the physical distance on the screen between lines that represent closer

distances (for instance red and purple) is larger than the distance between lines that represent further

distances (for instance green and cyan), then the FarNearRatio needs to be decreased to come closer

to the correct perspective.

Figure 5: Depth map with FarNearRatio tuned for a correct perspective

6.11

Range of interest

Usually objects drawn by an application are spread out between the Direct3D near and far plane.

However, some applications use only a small range of Z-buffer values for the majority of objects. This

may result in a depth map with only a few different depth values if the Visualizer uses the default

translation from Z-buffer values to depth information. The following settings can prevent this problem

by defining a range of interest for Z-buffer values. The Visualizer uses its entire depth range for just the

01 April 2009

16 of 26

Disparity value for objects that are furthest behind the display (ZFarInterest)

DirectX Visualizer

Table of Contents