Global Mapper, working with dgn format

Reading the dgn format is a standard in most of GIS or CAD programs, but several of these software (including Manifold GIS and gvSIG) are still reading the V7 format. AutoCAD and ArcGIS have already achieved it.


Let’s see how Global Mapper does it:

1. Reading dgn V7

It is interesting that files can be in a compressed archive of different extensions such as .tar, .zip or .tgz.

Once selected, the program asks for the projection to be assigned. Here you can choose from a comprehensive list, or from a file of type .prg or .txt that contains it. (It doesn’t recognize the internal projection assigned by Microstation Geographics)

Then, you can define the same projection assigned to all files selected. You can also generate a customized projection and save it as a .prj file, to call it at any time. It’s also attractive that, when you reopen a file without a clip_image002defined projection, as the program stores the last definition… Ohhhh, if Manifold could see these simple features!

But it remains in a painful situation, because it doesn’t read V8 like Manifold GIS and gvSIG, even with demand out there for this format and barely exist these two between those generated by MicroStation.

The texts will become as point objects, that’s the reason they have a point in the lower left node. You can’t edit objects, but you can touch, delete or edit vertexes; note that this is only possible at view level.

One annoying aspect of the import process is that, if the objects and the background are white colored, they will not be shown. To prevent this, you must assign a rare color to the background, this is done with command sequence: “view> background color …”

2. Exporting to dgn

The export process is not bad; this will send what is visible in the catalog of the “control center”, which is a way of calling the views organization. Everything will go clip_image003on the same projection.

Among the most annoying tasks, we can highlight texts’ sizes. To do so, you’ll be prompted to select a size and must test it. In case of the shape’s labels, they become texts to visible size.

It allows generating a 3D dgn if the map has elevation data; and then permits the option so that white objects can be seen as black or vice versa according to the background.

It also allows exporting in a matrix way, this is a very good alternative for oversized files. This causes files to be separated, and among the best, enables to send the grid reference, which may well be in geographic coordinates (latitude / longitude) or UTM.

The export process will have problems with complex objects, as in the case of shapes that have holes, because Microstation, for up to versions V8.5, continues handling these elements as complex shains or cells.

3. Extra options


It is worth mentioning that between the extra settings, you can define when importing to convert cells (cells or blocks) in points; if not, it will explode them as vectors.

You can also set the color number to be assigned as an attribute in the table, allowing underscore data by this criterion.

In conclusion, it is moderately acceptable. Although, Global Mapper does many other things, in this… it falls short.

You can download it from here.

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