Provide application program interface for development purpose.

VHCompare is not a simple comparison like comparing the two overlay pictures. It is a tool that will compare properties down to each CAD object. Apart from comparing object positions, it can also compare drawings properties like color, layer, character fonts, line-type, etc. There are varies options for comparison including base point comparison, object base comparison, paper space comparison, model space comparison, x-ref files comparison, etc. This is to ensure the comparison is comprehensive, precise and error free.

System Feature：
★Properties comparison:
The system will interpret each drawing property and combine with the CAD
technique to perform comparison. The system will provide varies comparison options.

★Properties enquiry:
Object property can be enquired in user interface to help user to better understand
changes. This is similar to CAD technique.Result is accurate and error free.

★Overlay viewing:
 To facilitate viewing final result, the system can provide different viewing options such as overlay viewing.

★ Export result to bitmap file:
User may select to export comparison result to a bitmap file for sharing or backup

★Application program interface is available for development purpose.

★Select area:
User may select a specific area for comparison without comparing the whole drawing file. This will speed up the comparison process.

★Select base point:
When user need to compare two files with greater difference, the system allow user
to compare two objects with selected base point.

★External Reference:
If DWG drawing file has Xref object, VHCompare will first remind user of the Xref file before choosing the comparison option.