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jjsigala8 post(s)
#31-Jul-20 21:02

I have several drawings that I created in Manifold many years ago, I'm trying to import them in QGIS to modify them and obtain areas, but the system mentions that the layers don't have a projection specified and they don't align well even when I specify different projections.

I know that this must be a basic questions for most people in the forum, but I hope that someone can give me a nudge in the direction to solve this issue.

Best wishes,

Jesus Sigala

Dimitri

6,104 post(s)
online
#01-Aug-20 05:29

You don't say what format the drawings are in, so that's where to start. After that, it's a question for QGIS people how to import data that is in whatever particular format the files are in.

If those drawings contain projected data and were saved into a format that does not automatically capture projection info, no GIS package can automatically assign the projection. You have to tell it what projection the data uses, because the format won't do that for you. The classic example is DXF format, a CAD format that doesn't save projection info.

If you save projected drawings into DXF format, to use that as an example, when you import those into *any* GIS, you have to tell the GIS package what projection it is supposed to use. That goes for Arc, Manifold, Q, and any other package.

That's a good reason to avoid using such formats or, at least, to make a point of jotting down somewhere the projection(s) used, so that on import into some GIS package in the future you can tell the package what projection it should use with that data.

If that is what's going on, carefully search your notes and try to remember what projection(s) you used. Read up on Q documentation carefully so you import the drawings correctly, and then use whatever procedure Q has for assigning projections to data from a format that does not automatically convey it.

tjhb

9,320 post(s)
#01-Aug-20 05:59

Or it could be another example of this. (A historical design failure we have to live with forever.)

jjsigala8 post(s)
#03-Aug-20 01:48

Thank you for your reply tjhb, I will do as Dimitri says and will also try your suggestion on exporting taking into account the local offsets and local scales.

Best regards,

Jesus

jjsigala8 post(s)
#03-Aug-20 01:45

Many thanks for your response Dimitri, and you are right that is a question for QGIS people. My files were produced in Manifold and I was not careful enough to export the prj files then. I will do as you suggested and get back to my old notes on the workflow so I can get the projection right.

Best regards,

Jesus

tonyw
595 post(s)
online
#01-Aug-20 08:07

Hi Jesus

Manifold offers a free M9 Viewer which you can use to open your old Manifold 8 .map file or open the individual drawing files if you have those separate. http://manifold.net/viewer.shtml if you are lucky the Info tab may shed some light on the projection used before. See the .jpeg attachment for where to find the Info tab. I attach the M9 .map file with a Bing Satellite layer for background, maybe see if when you import your drawing files, if they land where you expect them to land and see if it's the same or different from results when you use QGIS.

In my case the Info tab shows for projection: ESPG 3005, BC Albers projection.

My understanding is if you open an M8 .map file in M9 (Viewer or full version) you won't be able to open the same file in M8 again so use a copy of your original files.

Attachments:
Info on an area.JPG
M9 map file for finding out projection of old drawing.map

jjsigala8 post(s)
#03-Aug-20 01:53

Hi tonyw,

Thanks for your ideas on this. I just installed my old version of manifold 8 and will try to do it there. I hope I can.

Jesus

mikedufty

861 post(s)
#03-Aug-20 07:25

If you export as mif/mid QGIS seems to pick up the projection, and has the advantage over shape files that you keep column names more than 10 characters long. You may still need to fix the local offset/scale first.

QGIS won't edit mif format though, so you would then have to re-export to something Q works with better like geopackage.

If you have a postgresql database available you can access data in it both from M8 and QGIS, but I think there was some fiddling with extra dll files to get it working in Manifold, so probably not worth bothering if you just want to export rather than work on the same data in both.

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