System and method for multi-resolution raster data processing
An improved method and system are provided for constructing square multi-resolution tiles for use with spatial multi-resolution raster data. This improvement permits more efficient storage, processing and display of raster tiles at different resolutions. A base level cell size is defined for a highest required resolution. Lower resolution cell sizes are defined for lower resolution tiles. The lower resolution cell sizes are integer multiples of the base level cell size. A base level tile size is defined such that the integer multiples, as used in the step of defining lower resolution cell sizes, are all integer factors of a number of cells on a side of the base level tile. Using this technique, the boundaries for the base level tile and the multi-resolution tiles are coextensive.
1. A computer implemented method for constructing square multi-resolution tiles for use with spatial multi-resolution raster data, the method comprising:
defining a base level cell size for a highest required resolution;
defining one or more lower resolution cell sizes for lower resolution tiles, wherein the lower resolution cell sizes are integer multiples of the base level cell size;
defining a base level tile size wherein the integer multiples, as used in the step of defining lower resolution cell sizes, are all integer factors of a number of cells on a side of the base level tile;
sampling the spatial multi-resolution raster cell data at the highest required resolution;
storing the raster cell data sampled at the highest required resolution in base level size tiles;
sampling the spatial multi-resolution raster cell data at the one or more lower resolutions;
storing the raster cell data sampled at the one or more lower resolutions in respective multi-resolution size tiles; and
wherein the spatial multi-resloution raster data is comprised in a single compound file, the single compound file includes a master file table that includes data that defines a plurality of subfiles contained in the single compound file, the subfiles include a plurality of raster data fields which are comprised of event data,
wherein the event data is associated with a specific time marker and the event data indcludes data for a same geographic location at different points in time; and
wherein changes to event data are stored as new data with a new time marker, thereby allowing temporal changes and editing to raster data without need to form a whole new set raster data.
2. The method of claim 1 further including steps of:
determining a region of interest for display on a spatial map;
selecting and displaying tiles formed at higher resolution for tiles of the spatial map that include the region of interest; and
selecting and displaying tiles formed at lower resolution for tiles of the spatial map that do not include the region of interest, wherein tile boundaries for the higher and lower resolution tiles align without any spatial overlapping or gaps.
3. The method of claim 1 wherein the spatial multi-resolution raster data is stored in a data pyramid structure comprising a pyramid base level and one or more lower resolution overview levels.
4. The method of claim 3 wherein each level is arranged to include a spatial tile map that records what tiles exist in each respective level.
5. The method of claim 1 wherein the spatial multi-resolution raster data includes a plurality of fields, such fields including one or more of the following: RGB image data, numeric data, time data, text string data.
6. The method of claim l further including a step of using data compression to store the single compound file.
7. The method of claim 1 wherein the base level tile size is further selected to be a size closest to a size of 1024×1024 cells.
8. A computer system for constructing square multi-resolution tiles for use with spatial multi-resolution raster data, the system comprising computer storage for storing the spatial multi-resolution raster data and a processor with software configured for:
defining, using the processor, a base level cell size for a highest required resolution;
defining, using the processor, one or more lower resolution cell sizes for lower resolution tiles, wherein the lower resolution cell sizes are integer multiples of the base level cell size;
defining, using the processor, a base level tile size wherein the integer multiples, as used in the step of defining lower resolution cell sizes, are all integer factors of a number of cells on a side of the base level tile;
sampling, with the processor, the spatial multi-resolution raster cell data at the highest required resolution;
storing, in the computer storage, the raster cell data sampled at the highest required resolution in base level size tiles;
sampling, with the processor, the spatial multi-resolution raster cell data at the one or more lower resolutions;
storing, in the computer storage, the raster cell data sampled at the one or more lower resolutions in respective multi-resolution size tiles;
wherein the spatial multi-resolution raster data is comprised in a single compound file in the storage, the single compound file includes a master file table that includes data that defines a plurality of subfiles contained in the single compound file, the subfiles include a plurality of raster data fields which are comprised of event data,
wherein the event data is associated with a specific time marker, and the event data includes data for a same geographic location at different points in time, and wherein changes to event data are stored as new data with a new time marker, thereby allowing temporal changes and editing to raster data without need to form a whole new set raster data.
9. The system of claim 8 where the processor and software are further configured for:
determining, with the processor, a region of interest for display on a spatial map on a display;
selecting, with the processor, and displaying, on the display, tiles formed at higher resolution for tiles of the spatial map that include the region of interest; and
selecting, with the processor, and displaying, on the display, tiles formed at lower resolution for tiles of the spatial map that do not include the region of interest, wherein tile boundaries for the higher and lower resolution tiles align without any spatial overlapping or gaps.
10. The system of claim 8 wherein the spatial multi-resolution raster data is stored, in the storage, in a data pyramid structure comprising a pyramid base level and one or more lower resolution overview levels; and wherein each level is arranged to include a spatial tile map that records what tiles exist in each respective level.
11. The system of claim 8 wherein the spatial multi-resolution raster data includes a plurality of fields, such fields including one or more of the following: RGB image data, numeric data, time data, text string data, and wherein multiple bands of data are stored for more than one data field for raster data cell values.
12. The system of claim 8 wherein the processor is further configured to use data compression to store the single compound file in the storage.
13. The method of claim 5 wherein multiple bands of data are stored for more than one data field for raster data cell values.