CAD TO GIS TRANSFORMATION

Hi - unless you are working AutoCAD Map 3D it's unlikely that the CAD file has a coordinate system defined on it. In this case assuming the coordinates in the file are in the correct place then when you convert your data from CAD (perhaps DXF or DWG) then place a CoordinateSystemSetter transformer inline and set the parameter to the correct coordinate system. This simply tags each feature with the required coordinate system so that when you open your GIS file all the points should be in the correct coordinate space.

 

 

Hope that helps.

thanks Mr Dave..but can you tell me how to know the coordinate system used in survey plan from other company?actually, i have no idea to identify the coordinate system attach to the plan...

Hi,

 

 

I think you have two options

1. Ask them (probably the best option).
2. Make an educated guess based on the x,y coordinate values. Try to superpose the data visually over known terrain to verify your findings, e.g. by overlaying your data over a map service such as a cadastral WMS or Google Earth to check that it matches.

David

Yep - unfortunately you'll have little choice but to speak to the person who produced the data. CAD files typically do not retain any hints as to 'where' the data is. That detail is largely in the head of the CAD operator. If you can't get hold of that person immediately then assuming you know the name of the town or place on the map you could do a web search on an online map to find the location, then based on the country make an educated guess. I find this website useful as it allows you to do a keyword search too, so add a country name and hit 'Convert' and see which coordinate systems are suggested:

 

 

http://prj2epsg.org/ 

Hi Dave, thanks for your suggestion.but please let me know where to paste the wkt representation after we insert the city name?