This SAE Recommended Practice establishes three alternate methods for describing and evaluating the truck driver's viewing environment: the Target Evaluation, the Polar Plot and the Horizontal Planar Projection. The Target Evaluation describes the field of view volume around a vehicle, allowing for ray projections, or other geometrically accurate simulations, that demonstrate areas visible or non-visible to the driver. The Target Evaluation method may also be conducted manually, with appropriate physical layouts, in lieu of CAD methods. The Polar Plot presents the entire available field of view in an angular format, onto which items of interest may be plotted, whereas the Horizontal Planar Projection presents the field of view at a given elevation chosen for evaluation.
These methods are based on the Three Dimensional Reference System described in SAE J182a. This document relates to the driver's exterior visibility environment and was developed for the heavy truck industry (Class B vehicles, class 6, 7, 8 vehicles) although the projection principles presented in this document can be applied to any class of motor vehicles.
This document is intended to complement SAE J1050a and provides a visual format that can describe the driver's entire viewing environment. This environment can then be analyzed to determine what the driver is capable of seeing. It should be noted that one of the most important factors affecting the driver's field of view and the ability to make valid vehicle/design comparisons is the location of the driver's eyepoint. SAE J941 defines the Eyellipse which forms the basis for eyepoints chosen as the origin for Polar Plots and Horizontal Planar Projections. The Target Evaluation, Horizontal Planar Projection and Polar Plot create monocular evaluations. Projections/plots of multiple eyepoints must be overlaid to create binocular or ambinocular evaluations.
Analytical methods for creating Target Evaluations, Polar Plots and Horizontal Planar Projections for direct and indirect vision (planar and spherical convex mirrors) are presented. Note that it is possible to create plots and projections for other mirror surfaces and vision devices if the equations for determining reflection points are provided.