[Qgis-user] How do I register a Google Map?

[Mike Keelan]

OK I already have a .sid file for the area of interest, but if im going 
to use the coordinants as given from the Qgis program the data does not 
seem to be compatable with the GCP table info, or the Infor requested in 
the input dialog box to create the reference points for the .jpg 
raster.  ie the format from the Qgis main view is xxxxxxxx,xxxxxx  Is 
this projected Long,Lat  data?



Mike


On 2/5/2014 12:25 PM, Randal Hale wrote:
> So I work with Forestry guys and we do some very similar things when 
> georeferencing. You need a good point spacing - and typically I 
> describe that as a point at each coner of the image you are going to 
> georeference plus one for the middle or (sorry for using this example 
> but they have really good docs) - 
> http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=Georeferencing_a_raster_dataset 
>
>
> If it were me I would do this:
> 1. go to USDA Datagateway - http://datagateway.nrcs.usda.gov/ - and 
> download a NAIP image of your Area (sorted by county). It will be sid 
> format (probably) - so if you are on windows you should be OK for 
> opening up the image.
> 2. Use that to georeference the Google earth Screenshot. It will give 
> you a lot more control points than just your GPS.
>
>   * GPS can be notorious for not quite being right if you didn't way
>     point average - my forestry guys GPS property corners and that
>     makes me not happy every time they do it.
>   * Both Google and Bing are good and the open layers plugin rocks -
>     but - both image layers aren't captured (at least to me) with
>     mapping in mind - i.e. they may be questionable.
>
>
> OR
>
> 1. Download the GPX data from your unit using either QGIS or DNR GPS
> 2. Convert to shapefile.
> 3. Create your contours there using a new shapefile (digitize them in 
> again).
>
> I know I just glassed over a ton of technical by doing a 1 2 3 type 
> scenario but I think (just my opinion) there's more hair pulling than 
> you need to be experiencing (For the record I'm bald so I know all 
> about hair pulling).
>
> Yell if you need more help either off list or on list - I hope some of 
> this at least pushes you in a good direction.
>
> Randy
>
>
>
> -----------------
> Randal Hale, GISP
> North River Geographic Systems, Inc
> http://www.northrivergeographic.com
> 423.653.3611rjhale at northrivergeographic.com
> <mailto:rjhale at northrivergeographic.com>
> twitter:rjhale
> http://about.me/rjhale
> On 02/05/2014 12:04 PM, Mike Keelan wrote:
>> Thanks James,
>>
>> I got through the geo-referencing operation and  it did generate a 
>> new modified layer based on my .jpg.  However the new layer is badly 
>> distorted/stretched, (I used 4 coordinate Garmin GPS reference 
>> points), and it is not in the right location.  I can only find it by 
>> zooming to that layer extent.  I'm wondering if my coordinate data 
>> from my Garmin is consistent with what the geo-referencing program 
>> uses?  My Garmin data is xx.xxxxxx and it uses negative numbers to 
>> represent East instead of West.  Or, might there be an accuracy issue?
>>
>> I know my Garmin way-point data is good because it overlays on my 
>> Ortho almost perfectly as a separate layer.
>>
>> Mike K
>>
>> On 2/3/2014 8:28 PM, James Wood wrote:
>>> Mike,
>>> Here is a good tutorial overview of the georeferencing tool in QGIS:
>>> http://qgis.spatialthoughts.com/2012/02/tutorial-georeferencing-topo-sheets.html
>>>
>>> If the image is not in coordinate space, it will not line up with 
>>> your other data. so this operation will be necessary.
>>>
>>> Also, just as a side, I would think that an export from Powerpoint 
>>> would degrade image quality (depending on the original). I would 
>>> look at and maybe try for future use The Gimp (which is an open 
>>> source, free Photoshop-type application). It will give you more 
>>> control on export of not only various output formats but also pixel 
>>> and color depth, and the like. The official site is 
>>> http://www.gimp.org/.
>>>
>>> Best Regards,
>>> James
>>>
>>>
>>> ------------------------------------------------------------------------
>>> Date: Mon, 3 Feb 2014 19:59:14 -0500
>>> From: tmike.elhoa at comcast.net
>>> To: tech at wildintellect.com; etourigny.dev at gmail.com
>>> CC: qgis-user at lists.osgeo.org
>>> Subject: Re: [Qgis-user] How do I register a Google Map?
>>>
>>> OK, I installed the Open Layers plugin and it works very nice but it 
>>> won't do what I need, so let me be more specific and see if there 
>>> might be a remedy.
>>>
>>> The contour lines that I want were actually obtained using a hand 
>>> held Garman GPS.  The Garman data was overlaid on the Google map, 
>>> (with water depths), special integration,  then that map was 
>>> exported as a Jpeg, then imported to PowerPoint where a visual 
>>> interpolation was done to make the final set of contour lines for 
>>> the various lake water depths.
>>>
>>> My desire is the _digitize_ these contour lines as a set of separate 
>>> layers. ie 5' deep, 10' deep, etc. There are many good uses for 
>>> these layers,  but they must be accurate as to location and size.  I 
>>> don't think I necessarily need spacial info on the "map"/Jpeg if I 
>>> can get the whole map in the right position, and size, so I can do 
>>> the digitizing (which would then have the spacial info).  Then I can 
>>> discard the Jpeg.
>>>
>>> Is it hopeless?
>>>
>>> Mike K
>>>
>>>
>>>
>>
>>
>>
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>

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