Object Visibility Patterns in Low Level Flight
Abstract
Line of sight viewing angle, range and time distributions are given for a 70 kilometer sample of tree-top level annular (fisheye) imagery, and comparison made between these data and theoretical random single tree line of sight distributions. The effects of location over open and tree covered terrain are assessed, and limited data on the effect of altitude presented. Relative azimuth, elevation and range of objects when they first emerged into view were recorded by type of object. Relative angle of crossing linear features was determined, along with the duration that information of navigational value could be determined. When over trees the actual masking function was grossly different from the theoretical curves, while over open terrain actual masking approximated the five percent cover theoretical curve at close range and the one percent curve at 1000 meters. Over trees, masking for tank-size vehicles ranged from 83 to 93 percent, and over open terrain from 10 to 77 percent masking. Only 12.5 percent of linear features were found to be oriented within plus or minus 30 degrees of the nose at crossing, while 58.3 percent were within plus or minus 30 degrees of perpendicular to the nose. This finding implies viewing to the sides as an aircraft crosses features is necessary in order to see the feature details that will provide positive geographic orientation. The detailed viewing along linear features required for positive geographic orientation was available for an average of 24 meters, or one second at 50 knots. Limited data are presented on the effect of altitude on duration of line of sight to objects that provide information of value in geographic orientation. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1975
- Accession Number
- ADA016886
Entities
People
- J. N. Debonis
- Robert H. Wright
Organizations
- United States Army Aeromedical Research Lab