Contents
How does PostGIS support Simple Features for SQL?
PostGIS supports all the objects and functions specified in the OGC “Simple Features for SQL” specification (SFS). PostGIS extends the standard with support for embedded SRID information. 4.1.1.1.
How to calculate distance between Woking and Edinburgh using PostGIS?
I used ST_Distance_Spheroid in PostgreSQL (with Postgis) to calculate the distance between Woking and Edinburgh like as follows: I got a result of 592km (592,053.100454442 meters). Unfortunately, when I used various sources on the web to make the same calculation I consistently got around the 543km mark which is different by 8.2%.
Which is the best way to express an object in OpenGIS?
The OpenGIS specification defines two standard ways of expressing spatial objects: the Well-Known Text (WKT) form and the Well-Known Binary (WKB) form. Both WKT and WKB include information about the type of the object and the coordinates which form the object.
What do I need to use PostGIS with MapServer?
To use PostGIS with MapServer, you will need: Version 0.6 or newer of PostGIS. Version 3.5 or newer of MapServer. MapServer accesses PostGIS/PostgreSQL data like any other PostgreSQL client — using the libpqinterface.
Which is faster a PostGIS or a table?
For maps with relatively few features (100s), PostGIS will often be faster. For maps with high feature density (1000s), PostGIS will always be slower. If you are finding substantial draw performance problems, it is possible that you have not built a spatial index on your table.
What do you need to know about filter in PostGIS?
The filter must be a valid SQL string corresponding to the logic normally following the “WHERE” keyword in a SQL query. So, for example, to render only roads with 6 or more lanes, use a filter of “num_lanes >= 6”.