Dip and Slope Estimating Device (Patent No: 539013)

Inventor: Coombs, Vincent B. (assignor)

Location: Calgary

Comments: N/A

Description: Issued April 2, 1957

Vincent B. Coombs, Calgary, Alberta, Canada, assignor to Geophoto Services, Denver, Colorado, U.S.A. Application August 30, 1954, Serial No. 672,091 In the United Slates August 31, 1953.
11 Claims.

1. The method of ascertaining the slope of terrain viewed in three dimensions on a pair of stereoscopic aerial photographs by the use of a stereoscope which comprises employing on the photographs an instrument having straight lines spaced equally on opposite sides of a pivotal axis and capable of relative movement about the axis, and so positioning the lines below the stereoscope that a single line is being viewed, conditioning the instrument by a relative pivotal movement of the lines so that the single viewed line appears parallel to the slope of the terrain being viewed and the angle thereof to the horizontal which is desired to be ascertained, obtaining a reading of the angular relationship of the lines on the instrument, then obtaining the corrective relationship factor between the base-height ratio of the photographs and the focal length of the lens of the camera which was employed in taking the photographs and from this corrective relationship factor then obtain the actual angle of slope by using the factor to correct the instrument reading.

6. The method of ascertaining the slope of terrain viewed in three dimensions on a pair of stereoscopic aerial photographs by the use of a stereoscope which comprises employing on the photographs an instrument having straight lines spaced on opposite sides of a pivotal axis of two relatively rotatable sheets with the lines being equally spaced from the pivotal axis when the lines are parallel and capable of relative movement about the axis and so positioning the lines below the stereoscope that a single line is being viewed, conditioning the instrument by a relative pivotal movement of the sheets so that the single viewed line appears parallel to the slope of the terrain being viewed and the angle thereof to the horizontal which is desired to be ascertained, obtaining the angular relationship of the lines on the instrument, then obtaining the corrective relationship factor between the distance in inches between the photographs and the focal length of the lens of the camera which was employed in taking the photographs and from this corrective relationship factor then obtain the actual angle of slope by using the factor to correct the instrument reading.

7. An instrument for use in determining the slope of a terrain view in three dimensions on a pair of stereoscopic aerial photographs by the use of a stereoscope, said instrument comprising a pair of lines in parallel relation so spaced that they are viewed under the stereoscope as a single line, and means mounting the lines so that by relative movement the single viewed line may be caused to become positioned in parallel relation to the plane of the selected slope being viewed on the photographs.

9. The instrument of claim 7 in which the lines are each mounted on a transparent sheet of material with the sheets being pivoted together and the pivot being between the lines and at an equal normal distance from each line.