[Qgis-user] Primitive Troubleshooting

Tue Feb 28 02:37:06 PST 2017

Hi Stephen
OTF can be toggled on and off for each project (under project properties)
and a default setting is available under Settings -> Options -> CRS.
I´m not sure what causes your confusion with the canvas and layer list,
that is pretty similar to ArcGIS, the main difference is in the composer
where you design your maps.

Arni

Árni Geirsson
*Alta ehf* // +354 582 5000 // +354 897 9549

On 28 February 2017 at 01:14, Stephen Wandling <swandling at gmail.com> wrote:

> Arni,
>
> I guess because it seemed the obvious thing to do, I had been placing my
> raster layer first, in all of my projects.  I see now that if I place my
> Roads (or other local shape file) first, then when I place the raster
> layer, I see the correct EPSG of 26910 (OTF) in the lower right corner.
> And, everything aligns: Roads on the raster roads, etc.
>
> Is OTF always on or have I just not yet found where I might toggle it?
>
> When I export from Composer, I get the error message to export as raster.
> I have now learned that I can un-check Print as Raster in the error message
> and it allows exporting to a PDF in what I presume is vector?  Regardless,
> the PDF that is created is more than adequate for printing as a standard
> paper map.
>
> So, thank you for giving me the clues that allowed this to happen.
>
> I do have a nagging question: In ArcGIS, you have a Data Frame that you
> build your project in.  While I have searched for more info, it seems that
> in QGIS, the Canvass is the area to the right of the Layers panel?  That
> does not seem the way it should be.  E.g., if I push the layers to as
> narrow as it goes and arrange my project in the area to the right, if I
> then drag the Layers panel to make it wider, the Canvass would be cropped,
> when I would expect/want it to be compressed.
>
> What am I missing in regards to the size of the Canvass?
>
> Thanks again,
> Stephen
>
> On 27/02/2017 10:23 AM, Árni Geirsson wrote:
>
>> I'm not sure what went wrong in your process but I would think that the
>> safest route, to avoid CRS related problems, is to start a project in your
>> Roads CRS, include the Roads layer, then georeference your scanned map to
>> that same CRS and ultimately use the same CRS when you save the
>> georeferenced map. If you need to have the georeferenced map in a
>> different
>> CRS, then use the Warp tool afterwards.
>>
>> Arni
>>
>>
>> Árni Geirsson
>> *Alta ehf* // +354 582 5000 // +354 897 9549
>>
>>
>> On 27 February 2017 at 18:09, Stephen Wandling<swandling at gmail.com>
>> wrote:
>>
>>
>>
>>> Earlier I was trying to figure out why Composer wanted to export raster
>>> files, and I wanted vector.  I finally reduced my 'map' to the raster
>>> base
>>> map and one local shape file, Roads.  With this I found that selecting
>>> the
>>> layer Roads and using "Set Project CRS to this Layer" was causing
>>> Composer
>>> to default to raster output.  A clue!
>>>
>>> I had noticed that the raster base map rotated 2 or 3 degrees CW when I
>>> used "Set Project CRS to this Layer", above.  I also noticed that in
>>> Composer, if I had not used "Set Project CRS to this Layer", placing a
>>> UTM
>>> grid on my map resulted in the grid being rotated 2 or 3 degrees CCW.
>>> So,
>>> it appears that the grid is based on the base map?
>>>
>>> In reading today's posts, I noted mention of Georeferencer.  Digging into
>>> this, the tutorials, etc seemed to require having another input, to
>>> compare
>>> points.  I thought I might be able to accomplish this by comparing my
>>> Roads
>>> layer with the raster map.
>>>
>>> I loaded my local Roads shape file into a new canvass in QGIS and my
>>> raster base map into Georeferencer.  I would click a particular
>>> intersection in georeferencer and it would produce the 'enter
>>> coordinates'
>>> or 'get from map' options.  Selecting the latter, it switched to the map
>>> canvass and I could zoom in and click the same intersection.  This would
>>> send me back to the previous menu where the coordinates were filled in
>>> and
>>> I would select OK.  I did this on 4 points.  On the fourth point, I noted
>>> the red line angled 2 or 3 degrees CW, but quite long.
>>>
>>> I saved the points in a file and Started Georeferencing.  The completed
>>> raster base map came up on the QGIS canvass, along with the Roads shape
>>> file.
>>>
>>> What I saw did not please me.  In some places, the Roads were now falling
>>> at least 1/2 kilometer off from the base map road locations.  This put
>>> them
>>> in creek ravines and other hillshade elements.  The results were unusable
>>> for my purposes.
>>>
>>> When I had used "Set Project CRS to this Layer", the Roads layer fell
>>> onto
>>> the roads on the raster map.  Streams fell onto their ravines.
>>>
>>> Maybe I have to get another base map?  Or maybe my georeferencing method
>>> was faulty?
>>>
>>> Stephen
>>>
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>>>
>>
>>
>
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