Geo-reference problem

John Kennedy

We have been using the geo-reference feature quite a bit.  We use it in conjunction with Globalmapper.  It is very helpful in assembling base maps.  One issue I have noticed is a problem when we rotate the view.  If we keep north up, we can add new data in from Globalmapper and everything aligns.  However, on some sites due to shape etc. it is necessary to rotate the view.  I use the ucsfollow command to rotate the view (sometimes both in model and paper space).  If I do this, then add new data , such as a floodplain, the new data will show up elsewhere in space.  I have tried restoring the "world" view or "plan" view then inserting the new data, the view itself will change, but the coordinates are still off.  First, has anyone else experienced this?  Second is there a better way to rotate a view other than ucsfollow to preserve the world coordinantes?

Greg Skelhorn

John, I use command DVIEW to twist the view. You need to restore the world coordinates before inserting the new data.

Here is a little lisp routine I use that allows me to type in a rotation or click to pick and sets the crosshair orthogonal to the screen (not the most robust since I see I do not check the input):

(defun C:DTAlignView ( / my_error oeh oce ang dms)
    (defun my_error (msg)
        (if
            (not
                (member msg '("Function cancelled"
                          "quit / exit abort"
                          "console break"
                         )
                )
            )
            (princ (strcat "\nError: " msg))
        )
        (if oce (setvar "CMDECHO" oce))
        (if oeh (setq *error* oeh))
        (princ)
    )

    ;; Set error handler
    (setq oeh *error*)
    (setq *error* my_error)

    ;; Turn off command echo
    (setq oce (getvar "CMDECHO"))
    (setvar "CMDECHO" 0)

    ;; Prompt for an angle and twist the view.
    (setq ang (getangle "View twist: "))
    (command "_dview" 
        "" 
        "_tw" 
        (- (/ (* ang 180.0) pi))
        ""
    )
    (princ 
        (strcat
            "\nView rotation set to: "
            (angtos ang 1 4)
        )
    )

    ;; Set the SNAPANG so the cross hair is aligned
    (setvar "SNAPANG" ang)

    ;; Restore variables and error handler
    (setvar "CMDECHO" oce)
    (if oeh (setq *error* oeh))
    (princ)
)

John Kennedy

Thanks Greg, I will give it a try.

Richard Sands

I've just taken up Bricscad and am interested in GIS applications for this.

John (and others) I know this off-topic but what is the application you use please ('using the geo-reference feature')

John Kennedy

I have been using Globalmapper.   It exports (and imports) to BricsCAD very well.  I have not tried any of the add-on apps yet.

Richard Sands

Thanks John

I thought you may be just importing shp files.
I tried an ESRI import plugun and it worked OK for small data sets but crashed BC when importing a 16mb one.

It would be nice to import shp files but I expect you are working from dwg/ dxf export from GM and import to BC.
I may just do that and forget plugins unless I can find one that works and works well.

(Actually the 'Import' routine in BC is brilliant and fast. Thanks BC)

regards

Rakesh Rao

@ Richard : Did you find any utility to import an SHP file with the attribute info intact into Bricscad. The last I checked, SYCODE had a plug-in (listed in Bricsys applications catalog) that would only import the geometry part of the SHP and not the attributes (DBF info). A good plug-in to import/export SHP files from Bricscad is one of the long-standing requirements. Anyone has experiences?

Regards
Rakesh Rao
www.coordsys.com

 

Rakesh Rao

@John: What format do you bring in data from Global Mapper? Images? Vector?

- rakesh rao
- http://rakeshrao.typepad.com

 

Richard Sands

@ Rakesh Rao

I tried SYCODE but not succesfully.  Large 16mb data set crashed the program - dead as mutton.

Small ones come in OK but its 'dumb' and loses its attributes as you stated.

Yes a GIS module would make many people happy, particularly those working in the Gelogical area from what I gather talking to other GIS/ Graphic package users.

Canvas GIS and AI + MAPublisher are the only ones I know that succesfully comine such and are both good, MAPublisher is very good (IMO) but far more expensive and need AI to work inside.  Canvas GIS is all in one. (well it is if purchased as such)

regards

Richard

 

John Kennedy

I bring it in as a DWG file.  You want to go to FILE>EXPORT VECTOR DATA  Then you get a dialog box and you can choose your file format.  If you pick DWG you get a choice of versions.   You also have to choose the bounding option (by default, GM will export ALL data loaded).  For raster images you go to FILE>EXPORT RASTER IMAGES, again you get a choice of format.  For BCAD I have been using jpg, jp2 of GeoTIFF, all work very well.  Probably the coolest feature is the ability to bring in any raster image to GM, geo-rectify it (fancy term for rubber sheeting), when you then export as a new raster image you can bring it into BCAD and it is perfectly aligned and scaled.  By the way, Greg's script works very well.  Using the dview command seems to retain the georeferenceing.  Thanks Greg.