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J.P. Snyder

Publications and source records attributed to J.P. Snyder.

5 recordsLinked to original sources
USGS2010

The transverse and oblique cylindrical equal-area projection of the ellipsoid.

The formulas for the ellipsoidal projection are derived for both forward and inverse computations and consist of modifying the formulas obtained by using the authalic sphere so that the scale along the central line of the projection is constant. Fourier series are used to eliminate recurring numerical integration and other lengthy trigonometric computations of co-ordinates.-from Author

Annals of the Association of American Geographers↗
USGS1995

Map projections for global and continental data sets and an analysis of pixel distortion caused by reprojection

In global change studies the effects of map projection properties on data quality are apparent, and the choice of projection is significant. To aid compilers of global and continental data sets, six equal-area projections were chosen: the interrupted Goode Homolosine, the interrupted Mollweide, the Wagner IV, and the Wagner VII for global maps; the Lambert Azimuthal Equal-Area for hemisphere maps; and the Oblated Equal-Area and the Lambert Azimuthal Equal-Area for continental maps. Distortions in small-scale maps caused by reprojection, and the additional distortions incurred when reprojecting raster images, were quantified and graphically depicted. For raster images, the errors caused by the usual resampling methods (pixel brightness level interpolation) were responsible for much of the additional error where the local resolution and scale change were the greatest.

Photogrammetric Engineering and Remote Sensing↗
USGS1982

Geometry of a mapping satellite.

The proposed mapping satellite Mapsat is to consist of fixed fore, vertical, and aft linear detector arrays, any two of which may be used simultaneously to obtain digital images for one- dimensional stereo correlation. The satellite attitude may be varied according to Fourier series to enable a given detector on one array to follow closely the groundtrack sensed by the corresponding detector on another array throughout the orbit. These tracking errors are negligible for a satellite stable within anticipated ranges. The required computations have been programmed in FORTRAN IV. -Author

Photogrammetric Engineering and Remote Sensing↗
USGS1981

Map projections for satellite tracking.

New map projections to be used for plotting successive satellite groundtracks show these tracks as straight lines. The map may be made conformal along any 2 parallels of latitude between the limits of latitude reached by the groundtrack, or the 'tracking limits'. If these parallels are equidistant from the Equator, they may both be made true to scale, and a cylindrical projection results. If these parallels are not equidistant from the Equator, only one may be made true to scale, and a conic projection results. The groundtracks generally have sharp breaks at either tracking limit. If the tracking limit is one of the parallels at which the map is conformal, there is no break in the groundtrack, and the conic projection may approach (but cannot become) an azimuthal projection.-Author

Photogrammetric Engineering and Remote Sensing↗