Forum: Inkscape map units

Hello,

I'd like to draw the map of a building using inkscape, and overlay
my drawings with satellite views.

A batch program would then modify the map to adjust the position
of some points.

Then I would like to import the svg file into sketchup and use it
as a basis for quick 3d renderings.

And now the question: which units should I use for the canvas?

The building size is 50x15 meters. My first idea was to use this
size as the canvas, but for some reason, in such a case, inkscape
does not allow me to unzoom as much as I would like too (I cannot
have the full drawing on screen).

Is there as reson for this and a workaround?

I know many maps and GIS use SVG somehow, how do they choose their
basis unit?
A
Cheers

Hi,

 I think you would be better off using a GIS than Inkscape for the
 compilation of your map. QGIS would be a good, GPL based, software for
 your task. In a GIS you can better define your units and projection and
 then export to DXF, which can be read in Sketchup.

 The conversion of the GIS format (.e.g Shapefile, SpatiaLite, Postgis)
 to DXF may need manual conversion on the command line. OGR can help 
with
 that: http://www.gdal.org/ogr/drv_dxf.html - QGIS still needs some
 improvements for DXF import/Export.

 regarding SVG and units: in QGIS you can use SVG for several purposes:

 * point symbol definitions: You can use the SVG symbol and define its
 box in either map units or mm. The former scales with the zoom factor 
of
 the map, the latter stays at constant size, regardless of zoom factor.
 You can rotate and scale the symbols.
 * vector pattern definitions (uses the whole content of an SVG file,
 not a pattern definition) - you can repeat/scale/rotate the pattern
 * as a vector graphics in a map layout (print composer)

 In all of these options, you don't define the objects in map units, but
 rather paper units. QGIS uses the SVG and scales it, starting from the
 viewBox/width/height settings.

 Hope this helps,
 Andreas


 On Fri, 4 Mar 2011 09:25:21 +0100, Sébastien Barthélémy wrote:
>
> basis unit?
> _______________________________________________
> Inkscape-user mailing list
> Inkscape-user@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/inkscape-user

--
 --
 Andreas Neumann
 Böschacherstrasse 10A
 8624 Grüt (Gossau ZH)
 Switzerland

On Fri, 4 Mar 2011 09:25:21 +0100
Sbastien Barthlmy <barthelemy@crans.org> wrote:

> I know many maps and GIS use SVG somehow, how do they choose their
> basis unit?

I've just been doing some low level SVG map wrangling, but I just used
a 1200px canvas and a scale factor.  I knew the exact real world
dimensions of the original image, so you could work out the meters per
px for a given image size in px.

Cheers -Terry

On Fri, 04 Mar 2011 10:25:54 +0100
Andreas Neumann <a.neumann@carto.net> wrote:

>  I think you would be better off using a GIS than Inkscape for the
>  compilation of your map. QGIS would be a good, GPL based, software for
>  your task.

If you use QGIS, check out the OpenLayers plugin, which lets you put
Google and Yahoo imagery in the background.

Cheers -Terry

Hi,

On Fri, 4 Mar 2011, Andreas Neumann wrote:
> I think you would be better off using a GIS than Inkscape for the
> compilation of your map. QGIS would be a good, GPL based, software for
> your task.

Thank you for bringing qgis to my attention, but I'm not sure I'll use
it for this project: I already know how to use inkscape and how to
parse SVG, so I might simply go for SVG with a scale factor, as
suggested by Terry (thank you Terry!).

Moreover I still haven't succeeded to install qgis with macports. I'm
currently downloading the packages from www.kyngchaos.com, but it will
be my last try to get it running.

> In all of these options, you don't define the objects in map units, but
> rather paper units. QGIS uses the SVG and scales it, starting from the
> viewBox/width/height settings.

Thank you for these explanations, this is the kind of data I was looking
for.

Regards

On 03/04/2011 07:04 AM, Terry Brown wrote:
>
> Cheers -Terry

This might come in handy for that:
http://www.unitconversion.org/unit_converter/typography.html
http://www.unitconversion.org/unit_converter/typog...