Purpose
Allows a user to set options for an Isogram connection. You can issue this statement from the MapBasic window in MapInfo Pro.
Syntax
Set Connection connection_handle Isogram
[ Banding [ On | Off ] ]
[ MajorRoadsOnly [ On | Off ] ]
[ MaxOffRoadDistance distance_value Units distance_units ]
[ ReturnHoles [ On | Off ] ] [ MajorPolygonOnly [ On | Off ] ]
[ SimplificationFactor simplification ]
[ PointsOnly [ On | Off ] ]
[ DefaultAmbientSpeed ambient_speed
Units distance_units Per time_units ]
[ DefaultPropagationFactor propagation_factor ]
[ Batch Size batch_size ]connection_handle is a the number of the connection returned from the Open Connection statement.
distance_value is a Float value that specifies the maximum distance travel will be allowed to go off roads in the network.
distance_units is a string that specifies the distance units in which the specific distance_value is expressed. For a complete list of valid strings of distance units, see Set Distance Units statement.
simplification is a Float value that controls the density of nodes in the output region as a percentage. The value can be from 0 to 1 inclusive.
ambient_speed is a numeric value specifying the default ambient speed. The number is expressed in distance_units and time_units.
time_units is a string that specifies time units. Valid values are "hr", "min" and "sec".
propagation_factor is a Float value specifying the default propagation factor. The value can be from 0 to 1 inclusive.
batch_size is an integer expression that specifies the size of each batch that is sent to the service. The default is 2 and the maximum limit is 50.
Description
The Set Connection Isogram statement configures the connection that is to be used for creating an Isogram object (using the Create Object statement).
Banding applies only if multiple distances or times are specified in the Isogram operation. If On, the regions returned for one point will not overlap. The smaller region is cut out of the result. Thus it represents the time or distance from the smaller region edge to its edge. For example, if 10, 20, and 30 minutes Isograms are requested, the 20 minute Isogram represents the areas accessible from 10 to 20 minutes and the 30 minute Isogram the area from 20 to 30 minutes. If Off, all the regions cover the area accessible from 0 to the time or distance specified.
MajorRoadsOnly determines whether or not only major roads are used in the calculation of the Isogram. Isogram generation is substantially quicker when using MajorRoadsOnly.
MaxOffRoadDistance specifies the maximum distance travel is allowed to go off roads.
ReturnHoles indicates whether or not holes should be returned in the resulting region.
MajorPolygonOnly indicates that the Region returned has only one outer polygon.
SimplificationFactor specifies the reduction factor for polygon complexity. The simplification factor indicates what percentage of the original points should be returned or that the resulting polygon should be based on. The polygon or set of points may contain many points. The simplification factor is a float number between 0.01 and 1.0 (1 being 100% and 0.01 being 1%). Lower numbers mean fewer points in the region and therefore faster transmission times across the Internet connection. The default value is 0.05.
PointsOnly specifies whether or not records that contain non-point objects should be skipped.
DefaultAmbientSpeed is used only when specifying time. A syntax example is:
DefaultAmbientSpeed 12 "mi" Per "hr" DefaultPropagationFactor determines the off-road network percentage of the remaining cost (distance) for which off network travel is allowed when finding the maximum distance boundary. Roads not identified in the network can be driveways or access roads, among others. The propagation factor is a percentage of the cost used to calculate the distance between the starting point and the maximum distance. DefaultPropagationFactor is used only for Distances.
The default value for this property is 0.16.
The acceptable range is between 0.01 and 1.
Batch Size sets the number of records to send to the server to be processed at once. This may affect performance and responsiveness. If a large request is sent it will take longer for the Isogram to be returned and therefore longer for MapInfo Pro to respond to cancel requests and update the Progress Bar dialog box. A lower number improves responsiveness of the command and lowers the chance of a time-out and service failure. The default value is 2.
Example
The following example shows a Set Connection Isogram statement.
Set Connection iConnect Isogram
Banding On MajorRoadsOnly On MaxOffRoadDistance 2 Units "mi"
ReturnHoles On MajorPolygonOnly On SimplificationFactor .05
DefaultAmbientSpeed 50 Units "mi" Per "hr" DefaultPropagationFactor .2
Batch Size 2 Point OnSee Also:
Create Object statement, Open Connection statement