IOCA FS45 as an Output Format for Geographic Information Systems (GIS)
Original Publication Date: 2000-Dec-01
Included in the Prior Art Database: 2003-Jun-20
Unique characteristics of the newly defined Function Set 45 (FS45) in the IBM Image Content Object Architecture (IOCA) enable more efficient map generation. This print datastream format closely parallels the native data formats used in GIS. The format allows for high levels of data reuse at the printer. The format also ensures data integrity and allows for selective data availability. In a typical GIS map generation process, there are multiple input data layers representing multiple views of the same surface area. For example, aerial photographs, vegetation patterns determined from infrared satellite images, land use regions, text annotations, and transportation networks may all be present in the same map. Which data layers are presented and the order of presentation is dictated by how the hardcopy map will be used . Returning to the example, all users may want the aerial photograph at the base as a visual reference. Scientists may want to overlay vegetation patterns in turn overlaid by annotations to communicate findings with other scientists. For the same surface area, city planners may want to view land use regions overlain by transportation networks to project future growth. With IOCA FS45, each data layer can become a separate image content. Which data layer overlays which can be specified by the order in which the contents are defined. The external resource mechanisms in FS45 also can be extended so that an external resource specifies the order of contents and their offsets into the image, analogous to the way multiple tiles can be managed within each content. External definition also allows for subsets of all the contents stored in a master map to be selected. The advantage gained by multiple contents is that a single master digital map can be used to create hardcopy with multiple views, reducing disk storage requirements and computational cost of merging data layers. Tiles external to the IOCA object can be included by contents and managed as object containers in the Mixed Object Data Content Architecture (MO:DCA) and as Data Object Resources (DOR) in an Intelligent Printer Data Stream (IPDS). A map generator directly controlling an IPDS printer or using a print server such as IBM Infoprint Manager can capture these resources at a printer. No matter how many copies of how many different versions of the map are created, the data only has to be downloaded once, and can be downloaded prior to map generation. Each tile can be compressed with a different algorithm, for example G4 for photographs and LZW for text. Distinct regions within a single content can be split into tiles that separately trade off data loss, compressibility, and computation costs of compression or decompression. Homogenous regions can be represented simply by a color and a tile transparency mask. Only tiles that change need to be downloaded to the printer when maps are updated. The advantage gained is less data manipulated less often, eliminating the typical bottleneck in data transfer from map generator to output device. Because captured DORs are uniquely referenced by Object IDentifier (OID), and an OID can encode a checksum , an exact lineage of each image component can be tracked to ensure data integrity. When a tile is included, an inclusion transparency mask can be employed to selectively obscure features from a tile without changing the content of the tile. The advantage gained is that security procedures within an organization can be enhanced without additional cost or effort.