2015 Geolocation

[russ.green]

I've just been experimenting with the Geolocation tools in AutoCAD 2015 and I've noticed a bit of an issue with the data here in the UK.

Its common practice to treat the origin of the World UCS as the origin of the Ordnance Survey national grid.

The Geolocation dialog gives me the latitude and longitude of the dropped marker. So using http://gridreferencefinder.com/ this can be converted to the OS National Grid X,Y.

E.g.  50.2641,-5.1090 converts to 178520,045084 (178520000,045084000 as architects here tend to work in millimeters).

Placing the geolocation marker at World UCS coordinates 178520000,045084000 in a mm file should locate the live map in the correct place for us to overlay the digital mapping data obtained from the Ordnance Survey.

Some experiments in the Bristol area (in the regaion of 51.44, -2.59) I found the livemap data was about 5m too far west and 1m too far south.  Easily fixed by tweaking the marker position.  I've tried the different coordinate systems that seem to relate to the UK and make no difference.

However,  when testing on a location in Cornwall using the coordinates above the data was not misplaced by much but the rotation was well off. Actually nearly, but not exactly, by the amount of magnetic variation in that location (approx 2.6 degrees).  Correcting this roation showed the OS map lining up reasonably well with the live map.  But this didn't solve my placement issues in the Bristol area.

Its not clear from the documentation how the live map handles north and how, if at all, the application of a GIS Coordinate system should correct magnetic to true or grid north.

Can anyboby shed some light on this?

[jggerth1]

Bing is not accurate.  It's not precise, and it's not reliable.  

While adequate and very handy for preliminary planning (very preliminary!!!!) attempting to rely on the imagery imported for anything beyond that is fraught with potential for errors of vaying magnitude,  In 2014 I've come across locations where the Bing imagery used aby GeoMaps was off a couple of miles., (2015 appears to have improved there.... but a handful of meters is nothing unexpected.)

For real puposes, you will need to use real georeferenced imagery, and will need to place that accurately.  Might I suggest either Raster Design or Map3D/civil3D?  while ther'ss additional cost, it's a lot cheaper than sitting in court trying to explain why you relied on known unreliable background imagery for design.

[russ.green]

its not something I would have even bothered with if it hadn't appeared in the software and probably one of the few things I would likely still use AutoCAD for

[robert]

I'm experimenting with it as well and have am having problems with resolution. In the 2015 version there is the capability to capture an area of the map that remains inside the drawing. However, I find the captured image has a much lower resolution than the displayed map that you cannot print.

Anyone having this problem or now of a solution or if it is even possible.

[russ.green]

You can adjust the resolution...select the captured area and look at the ribbon panel that appears...




Sent from Samsung tablet

[robert]

I've tried adjusting from coarse, optimal, fine and very fine, nothing seems to improve the quality to same display quailty.

Not sure if it's a propriety map issue or what. had really high hopes with this new feature. It works great if you just need to

overlay a drawing, but the printing quality seems to be really lacking.