I have imported a number of Shapefiles from the ordnance survey using shape2SQL
These have been imported as geometry however i would like to convert them to Geography and specifically to srid 4326
the shape when imported contains a number of polygons
ultimately i'm trying to ascertain if a number of lat/long coordinates i hold fall within one of these polygons (so i suppose i also need to alter the coordinates to geog (which i can see has been answered before))
finally the plan is to display this on an SSRS report or onto a Bing Map display (hence why at this stage i believe i require SRID 4326)
How do I import the shape as SRID 4326?
Best Answer
You cannot do that.
Geometry and Geography are two completely different types of data. You probably did read up on it..., but here is an explanation...
Geometry are points on a flat surface. If you would like to calculate the area of your bedroom, i.e. 3.5m by 6.8m, it would result in 23.8m2 - if you would have drawn it in a CAD program, you would start from 0,0 and draw a rectangle to 3.5 in width, and 6.8 length, which gives you the area of the flat surface, on a Z elevation of 0
When you get to Geography, we are talking about the way the earth or sphere are measured. Yes, the earth is round, but not completely round as a ball. It actually looks like a potato mixed with a watermelon. So, when you draw lines on the earth's surface, they are not flat. For the first couple of meters, its "ok" to measure a flat line, but after that you have to consider using calculations and Coordinate systems (i.e. WGS84, a.k.a. 4326 SRID)
Explanation: http://en.wikipedia.org/wiki/Earth_radius | http://en.wikipedia.org/wiki/Horizon
When you store something in Geometry, they are normally X,Y,Z, and when you store something in Geography they are normally Latitude, Longitude, Elevation. Also to note is, when you store in Geometry it is usually in units of measure, i.e. Meter. When storing in Geography is is usually in which datum the data reside, for example a province or state in America would not the be the same area if measured in Australia. The earth's curve is not the same, and you would sit with errors in your calculations. So, the idea was to use WGS84 as the major measuring unit across the world, but that has led to many errors locally on the ground for some surveyors. Measuring with a theodolite instrument, you would calculate the correct area of a surveyed place to the accuracy of less than 0.002m - which is acceptable. Imagine measuring an area of a place by only having 3 decimal digits after a lat/lon.
shape2SQL has a selection where you can choose between the two. BUT, you cannot compare the two against each other...