How to import .DXF file into Deed Calls Pro
July 12, 2016 Leave a comment
“My specific problem seems to be getting my .dxf file into the correct Datum or Coordinate System so it matches with the satellite images in Deed Call Pro. What I’m working with is a typical surveyors CAD file that contains a boundary and topological contours but may not be
keyed to any specific coordinate system. I was hoping to find some software that would allow me to convert this type of ‘plat’ into something that could be used in Deed Calls Pro app. It seems like your PC-GIS software would have this capability, so I’m just trying to confirm this and test it before I purchase in case I’m misinterpreting something.”
Some CAD systems allow you to save the plat in a specified coordinate system. In this way, the plat is geo-referenced and can be
brought into a map at the correct location. The satellite image provided on iPad is based on WGS84 datum and LLA coordinate system.
As your .dxf files are not geo-referenced, you will need to first geo-reference them before they can be loaded to the correct location on a map.
PC-GIS X provides two ways to achieve this.
1. The Register Photo/Image function will let you geo-reference an aerial photo or any other map image against a handful of known control points. The process is illustrated in this Geo Referencing Demo video.
If you take an image of your dxf plot (.tif or .jpg), you can try this function in the PC-GIS DEMO program if you know the approximate coordinates of the four corners.
In the official PC-GIS X program, you would then save the geo-referenced image as a .pim file that can be loaded into Deed Calls Pro.
2. PC-GIS X will let you create a local NEZ coordinate system that is geo-referenced so that your .dxf file can be loaded correctly in this local system. Basically, the program will let you match the X-Y coordinates of two opposite corner points of your .dxf map with the corresponding GPS coordinates (LLA). If you used PC-GIS X to create the NEZ system, transfer the user_pla.sys file from the PCGISX folder to the Documents folder for Deed Calls Pro; then the local NEZ coordinate system will be available in Deed Calls Pro. After loading the .DXF file in the NEZ coordinate system, you can switch to the LLA coordinate system and turn on the built-in Map.
With either procedure, it’s important to use the correct distance unit (the one that your .dxf file uses).
It is probably easier to create a local NEZ (Y-X-Z) coordinate system as you will only need to establish the relationship with the actual GPS LLA coordinates at the two opposite corners of an area of reasonable size covering your job site.
In fact, Deed Calls Pro and some of our other iPad apps (e.g. iCMTGIS II/II/PRO, Forester GPS GIS II/III and Farming GPS/GIS II/III) also provide the ability to create a local NEZ coordinate system. Say your job site is contained within a square of 2000 m on each side. We could call the lower-left corner of the square point A, and the upper-right corner of the square point C. In your NEZ system you could assign (1000,1000) to point A and (3000,3000) to point C. Then you would get the GPS LLA coordinates at points A and C by using an accurate GPS receiver. After creating the local coordinate system, you should then be able to import your DXF file into this NEZ system then switch to the LLA system and confirm that the elements of the drawing at the correct physical locations.