Chapter 6
Coordinate Search Logic
Rule 3: If there are no applicable POS, STN, or Pos view records, the SRX will use the most recent OBS, MC or RED record. The record's view is no longer significant. The SRX will look for any OBS, MC or RED records, starting at the end of the current job and going backwards in chronological order. If the SRX finds an OBS, MC, or RED record in its search, it will reduce it to coordinates (see Chapter 28, SDR Database). Rule 4: If no such record can be found, the search fails. If the SRX cannot find any POS, STN, Pos view, OBS, MC, or RED records for the point in question, the search fails and the SRX assigns Null coordinates. An aborted set may leave OBS records on the database, but these OBS records are ignored in database searching. Rule 5: Coordinate searching is iterative. Finding the coordinates of the point may necessitate finding the coordinates of several other points. This process will continue until a fixed position for some point (a POS or STN records, not a Pos view record) is found. The number of iterations that the SRX can perform are limited. The search fails if the SRX has no coordinate more than 25 points before it can coordinate the original point in question.
6.2
Applying Coordinate Search Rules The intelligent SRX search rules will give you some useful results. Once you understand the search rules, you will probably think of even more ways to use the SRX to solve surveying problems: Example 1 When setting up on a new station, just enter the point name. The SRX finds the coordinates automatically and calculates them if there is just an observation to the point. Example 2 When a traverse is adjusted, all the sideshots are automatically adjusted (assuming they were stored in Pos view). This is true because the traverse program stores updated coordinates for each station on the route. When the sideshots are output, the search for the station point finds the adjusted coordinates, and the calculation produces adjusted sideshot coordinates. Example 3 Cadastral surveyors may key in one starting coordinate and then a sequence of azimuths and distances as marked on a plan. In the field, any one of those points may be used as a station or reference point. The SRX's iterative search (Rule 5) automatically calculates the desired coordinates. Example 4 If topography is done from a station, and the coordinates of that station are subsequently improved (perhaps by averaging or keyboard input of a new position records), then the coordinates of the topo points will be updated appropriately during comms output or when displayed in review.
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SRX