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The SEDRIS Data Representation Model
APPENDIX A - Classes Spatial Resolution LOD Data |
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An instance of this DRM class specifies the spatial resolution of the associated data, which governs the switching of objects by a spatial-resolution-based <LOD Related Geometry> or <LOD Related Features> instance.
NIMA Digital Terrain Elevation Data (DTED) is produced at a number of standard spatial resolutions: 30 arc seconds, 3 arc seconds, 1 arc second, 0.3 arc second, and so on. Although the spatial resolution of the longitudinal axis varies with latitude, the spatial resolution of the latitudinal axis is fixed (and equals that of the longitudinal axis at the equator).
Atmospheric data sets are often produced in an Augmented Projection- based SRF, such as ALCC (Augmented Lambert Conformal Conic), at a number of standard spatial resolutions, such as 81 kilometres, 27 kilometres, and 9 kilometres.
The <Map Scale LOD Data> class can be used in some cases as a "rough" approximation. Unfortunately, many data sets require more precision.
For example, while <Map Scale LOD Data> can be reasonably applied to lower-resolutions of DTED (e.g., levels 0, 1, and 2), it doesn't apply well to higher resolutions of DTED. (It doesn't apply at all to bathymetric and atmospheric data).
In this case, normally the highest resolution is to be used.
| SE_Long_Float | spatial_resolution; | (notes) |
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| SE_Spatial_Index_Spacing_Unit | unit; | (notes) |
The spatial_resolution field specifies the spatial resolution of the associated data, and shall be a positive value.
The unit field specifies how the spatial resolution value is measured.
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