[Qgis-user] Qgis-user Digest, Vol 138, Issue 21
Anina Henggeler
aninahenggeler at gmail.com
Fri Aug 18 00:30:01 PDT 2017
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> Today's Topics:
>
> 1. Transform not solvable (Charles Barrows)
> 2. Re: Transform not solvable (Andre Joost)
> 3. Re: background transparency (Richard McDonnell)
>
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Wed, 16 Aug 2017 15:53:02 -0600
> From: "Charles Barrows" <charles.barrows at Comcast.net>
> To: <qgis-user at lists.osgeo.org>
> Subject: [Qgis-user] Transform not solvable
> Message-ID: <01a001d316da$087986a0$196c93e0$@Comcast.net>
> Content-Type: text/plain; charset="utf-8"
>
> I have a Georeferencer raster scan with 9 data points arranged in 3 rows of
> 3. I've checked the points out on the image for consistency of sequence,
> both x & y's, and they look good.
>
> When I push the transform button I get the message "..:transform not
> solvable." I did make some mistakes while placing some of the data points,
> for which I deleted the bad ones and added new ones. Could the transform
> program be confused because the locations are now in a random order in the
> GCP table, or could it be something else?
>
> Charley
>
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> Message: 2
> Date: Thu, 17 Aug 2017 15:13:14 +0200
> From: Andre Joost <andre+joost at nurfuerspam.de>
> To: qgis-user at lists.osgeo.org
> Subject: Re: [Qgis-user] Transform not solvable
> Message-ID: <on44tn$e2s$1 at blaine.gmane.org>
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>
> Am 16.08.2017 um 23:53 schrieb Charles Barrows:
>> Could the transform
>> program be confused because the locations are now in a random order in the
>> GCP table, or could it be something else?
>>
>
> I don't think so. It might be a matter of the Transformation type you
> have chosen.
>
> HTH,
> André Joost
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Thu, 17 Aug 2017 17:04:54 +0100
> From: Richard McDonnell <richard.mcdonnell at opw.ie>
> To: Brett Adams <badams at spinifexgpx.com.au>, qgis-user at lists.osgeo.org
> Subject: Re: [Qgis-user] background transparency
> Message-ID: <5995BEA6.5010802 at opw.ie>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> Brett,
> There appears to be nothing wrong with those examples, if there where,
> you would be informed anyway!
> Another approach try this /*gdal_calc.py -A input.tif
> --outfile=result.tif --calc="A*(A>0)" --NoDataValue=0
> */This supposes of course, you are familiar with command line GDAL!
>
> Might I suggest another solution, It will only work with other QGIS
> users, but If you, in Properties, save your style as default, it will
> create a default qgis style with the same name as the raster. When you
> send it along with the raster, or anyone opens the raster, where the
> style is in the same location, the raster will always open as you require.
> Without having a subset of your dataset to play with Im sorry, I cant be
> of any more help!!
> Regards,
>
> Richard.
>
>
>
> On 16/08/2017 03:32, Brett Adams wrote:
>>
>> Hi Richard,
>>
>> Trialled your suggestion and others contained in the
>> gis.stackexchange.com link. Always get the same result where if any
>> of the three bands contain a 0, it’s removed.
>>
>> Maybe I’ve got the syntax slightly wrong?
>>
>> *Original *
>>
>> gdalwarp -overwrite -s_srs EPSG:28351 ""C:/Brett.tif"
>>
>> *Trialled variations*
>>
>> gdalwarp -overwrite -srcnodata "0,0,0" -dstnodata "0,0,0" -s_srs
>> EPSG:28351 -of GTiff "C:/Brett.tif" "C:/Brett2.tif"
>>
>> gdalwarp -overwrite -srcnodata "0,0,0" -dstnodata "0,0,0" -of GTiff
>> "C:/Brett.tif" "C:/Brett2.tif"
>>
>> gdalwarp -overwrite -srcnodata None -dstnodata None -dstalpha -s_srs
>> EPSG:28351 -of GTiff "C:/Brett.tif" "C:/Brett2.tif"
>>
>> Brett
>>
>> *From:*Richard McDonnell [mailto:richard.mcdonnell at opw.ie]
>> *Sent:* Tuesday, 15 August 2017 11:17 PM
>> *To:* Brett Adams; qgis-user at lists.osgeo.org
>> *Subject:* Re: [Qgis-user] background transparency
>>
>> Hi,
>> Just looking into this, but you might try whats outlined here
>>
>> https://gis.stackexchange.com/questions/166699/replacing-rgb-value-0-0-0-with-nodata-nodata-nodata-in-gdal
>>
>> Warp, can be found under *Raster*, *Projections*,*Warp *fill in the
>> fields just as you done before for the Translate, with the exception
>> of the nodata field.
>>
>> At the bottom where you see the GDAL script being constructed, you
>> should also see a Pencil or Pen icon, select this, it will allow you
>> to directly edit the script.
>> You should paste */-srcnodata "0,0,0" -dstnodata "0,0,0" /*just
>> after*/-overwrite /*so as you have something like below*/.
>>
>> /*gdalwarp -overwrite -srcnodata "0,0,0" -dstnodata "0,0,0" -of GTiff
>> raster_in.tif raster_out.tif
>>
>> Hope this helps.
>>
>> Regards,
>>
>> Richard.
>>
>>
>>
>> On 15/08/2017 13:42, Brett Adams wrote:
>>
>> Richard,
>>
>> Thanks for your response. Gave this a run but it’s not quite
>> working.
>>
>> Looks like the problem stems from the colour being defined across
>> three bands, with black defined by 0,0,0
>>
>>
>>
>> When “No data = 0” this clears all colours where band 1 = 0.
>> Which includes a lot more colours than just black.
>>
>> Tried entering a few different formats to cover the all 3 bands
>> but the second 2 are always ignored.
>>
>> Any thoughts as to how I get 3 bands recognised?
>>
>> Brett
>>
>> *From:*Qgis-user [mailto:qgis-user-bounces at lists.osgeo.org] *On
>> Behalf Of *Richard McDonnell
>> *Sent:* Monday, 14 August 2017 10:16 PM
>> *To:* qgis-user at lists.osgeo.org <mailto:qgis-user at lists.osgeo.org>
>> *Subject:* Re: [Qgis-user] background transparency
>>
>> Brett,
>> Apologies, ive just realised your version of QGIS may not have the
>> processing toolbox.
>> You may also do this by going to *RASTER*, *Conversion *and
>> selecting*Translate *Its the very same tool just a different interface
>> Regards,
>>
>> Richard
>>
>> On 14/08/2017 15:04, Richard McDonnell wrote:
>>
>> Hi Brett
>> You can indeed, just use the Processing toolbox, just type
>> Translate into the search box and select the Translate Tool
>> under GDAL.
>> The values you specified as transparent, can be specified
>> under the Nodata Value
>> You can also do this as part of a batch if you have a number
>> of files, you wish to do this for.
>>
>> Hope this helps,
>>
>> Richard.
>>
>> On 14/08/2017 14:07, Brett Adams wrote:
>>
>> Hi Folks,
>>
>> I have a geotiff that contains a black ground in areas
>> where there is no data. The black background is made
>> transparent within QGIS via “Layer Properties – Transparency”
>>
>> Can I export a new Geotiff with the black background removed?
>>
>> I’m running 2.6.1 On Windows-7. Yes, I know it’s an old
>> version but I’ve had no reason to update. So far…
>>
>> Thanks
>>
>> *Brett Adams*
>>
>> *Spinifex-GPX*
>>
>> *0438 861 974*
>>
>>
>>
>>
>>
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>> --
>> *_Richard McDonnell_*
>> *GIS Specialist PgD GIS AssocSCSI*
>> *OPW FRM Data Management*
>> *52 Stephens Green, Dublin 2.*
>> TEL: 01 6476543
>>
>> <http://www.opw.ie/>
>>
>>
>>
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>> --
>> *_Richard McDonnell_*
>> *GIS Specialist PgD GIS AssocSCSI*
>> *OPW FRM Data Management*
>> *52 Stephens Green, Dublin 2.*
>> TEL: 01 6476543
>>
>> --
>> *_Richard McDonnell_*
>> *GIS Specialist PgD GIS AssocSCSI*
>> *OPW FRM Data Management*
>> *52 Stephens Green, Dublin 2.*
>> TEL: 01 6476543
>>
>
> --
> *_Richard McDonnell_*
> *GIS Specialist PgD GIS AssocSCSI*
> *OPW FRM Data Management*
> *52 Stephens Green, Dublin 2.*
> TEL: 01 6476543
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