Licensing options for this format begin with FME Desktop Professional Edition.
The TOBIN TDRBM II Data Distribution Format Writer allows FME to write TDRBM II Data Distribution Format files.
This chapter assumes familiarity with the format specification. You can locate the TOBIN TDRBM II Data Distribution Format Specification Version 2.4 1-28-1998 at http://www.tobin.com/marketing_pages/documents/data_formats/tobin_tdrbm2.html.
Overview
The TOBIN TDRBM II Data Distribution format, commonly called TDRBM II, provides an enhanced graphical representation of TOBIN Survey information.
This format is an ASCII text-based format that supports the storage of point, line, polygon and text features as entities (features) in its data files. In the TDRBM II file structure, entities are composed of sequential groups of structured column-aligned attribute records. Each entity consists of one header Record (Record Type 0), followed by zero or more annotation records (Record Type 2), and a sufficient number of coordinate records (Record Type 3) to specify the boundary of the entity. Each record begins with a single character indicating the record type. This attribute field can take the value of “0”, “2”, or “3” and specifies the type of the information contained in the record as either header, annotation or coordinate information. User-defined attributes are not supported by this format.
All header records have similar formats but differ slightly depending on the value of the Name Format Type (column 4) attribute value of the header record of an entity. This value corresponds to the survey system of the data as described within the TDRBM II specification and can take the value of exactly one of the following integers: 0, 1, 2, 3, 4, 5 or 6. In turn, this value determines the type of information stored in columns 5 to 32 of a particular header record.
All annotation records have the same format and can store up 32 right-justified ASCII characters.
All coordinate records have the same format. Each coordinate record stores a pair of coordinate values and represents a line segment. Consequently, a series of sequential coordinate records can be interpreted to construct point, line, or polygon boundaries.
Note: This chapter uses the terms entity and record in the manner outlined by the TOBIN TDRBM II Data Distribution Specification Version 2.4 1-28-1998.
Writer Overview
FME considers a TDRBM II dataset to be a collection of TDRBM II files contained in a single folder. The TDRBM II writer creates and writes feature data to the folder specified by the Dataset parameter.
Existing TDRBM II files with the same file base name as the source file base name are overwritten with the new feature data.
Creating TDRBM II entities which contain annotation records requires the linking of source annotation features to source geometric feature with a potentially many to one relationship. This is accomplished by matching the ID attribute value of source annotation features to the ID attribute of a source geometric feature (point, line or polygon). To produce meaningful results, the following two conditions must be met:
- The Id attribute value of the source annotation feature must equal the Id attribute of the source geometric feature.
- Features received by the writer must arrive in sorted order based Id value.
Orphan annotation features, that is, annotation features not specifying an Id value or annotation features with an Id value not equal to the “current” geometric feature Id value cannot be written and are dropped. Discarding orphan text features is a consequence of the TDRBM II format, since it does not support “standalone” annotation records. The result is that orphan annotation features cannot be written to file as entities.
Producing a meaningful TDRBM II file output will require setting up a custom mapping file that describes the details of your input schema for the following reasons:
- Generic (automatic) translations usually work for most formats because they are so simple. (If a road has an attribute “length” in the source, it makes sense to make an attribute called “length” in the destination.) However, TDRBM II is a special case. TDRBM II contains numerous output format attributes which make a "best guess" impossible. Translating most formats does not require the understanding of the output format schema, just knowledge of it.
- TDRBM II has numerous predefined attributes and values that features can have. When FME is given a source dataset without any indication of which attributes in the source data should be used to fill in the required attribution in the output TDRBM II file, most of this information will be lost. (There is no way to “guess” at the Logical Level value for any given entity when all it is given is a source file with no knowledge of the meaning of the schema or input data.) Therefore, an "automatic" translation will usually not generate anything useful. What needs to happen is that a user needs to create a custom mapping file that tells the FME where to find all the required TDRBM II data within their specific source dataset.