[Qgis-user] downloading a wms geoservice from QGis

Tue Nov 8 22:21:36 PST 2016

Hi Juliana, 

Not sure if you figured it out already. But smaller resolution means
better quality and larger file sizes. A resolution of 0.05 degrees means
that each pixel is 0.05 degrees in width and height. Gradually make this
value smaller until you are satisfied and still works. At some point the
WMS may refuse to server or your file will get too big. 

About projection: it is generally not advised to work with EPSG:4326
projection. Depending on the area you work with, I would switch to a
meter based projection, such as UTM zones. 

Greetings, 

Andreas 

On 2016-11-07 22:33, Juliana Mori wrote:

> Yes, I did set a resolution as you explained:
> 
> I could finally get a file but the resolution is too poor (all pixelized)> I tried with none compression but still not good. I guess the horizontal and vertical resolutions are too low, but don´t really understand the parameter to be sure what would be a good value. Any sugestions? 
> 
> 2016-11-07 19:27 GMT-02:00 Andreas Neumann <a.neumann at carto.net>:
> 
> So - have you tried setting a resolution and extent? The resolution input fields need to have values. Empty fields don't work. And no - QGIS can't autodetect it. It does not know the native resolution of WMS services.
> 
> Andreas
> 
> Am 07.11.2016 um 22:23 schrieb Juliana Mori: 
> sorry, I hit enter before finishing the email... Again:
> 
> Hi Andreas,
> 
> for sure it would be much better to use the webservice directly but I´m already investigating with CARTO and it seems there´s no WMS support - if I have any update on this, I´ll share with you.
> 
> EPSG:4326 would be perfect for me, even though I know the original file is in Magna Sirgas (EPSG:4686). So, if I understood right, I need to specify a resolution in decimal degrees, right?
> 
> I´m saving a raster image with only 3 color values (assigned by its column "dn" which indicates if the pixels correspond to forest, no forest or no information). Sorry, I don´t know to say if it´s orthoimage.
> I´ve already polygonized the other tiff files I had from this series (but were not from WMS) and the results were meaningful, probably because there´re only this 3 colors.  
> 
> 2016-11-07 19:18 GMT-02:00 Juliana Mori <julmori at gmail.com>:
> 
> Hi Andreas,
> 
> for sure it would be much better to use the webservice directly but I´m already investigating with CARTO and it seems there´s no WMS support - if I have any update on this, I´ll share with you.
> 
> EPSG:4326 would be perfect for me, even though I know the original file is in Magna Sirgas (EPSG:4686). 
> 
> 2016-11-07 19:15 GMT-02:00 Andreas Neumann <a.neumann at carto.net>:
> 
> Hi Juliana, 
> 
> First, I would investigate with Carto, if you really cannot embed a WMS. It would be much better to use the webservice directly rather than downloading and uploading and then end up with an outdated image. 
> 
> If that does not work, you need to set a meaningful resolution. As we can see in your screenshot the resolution text input fields are empty. Also check if the projection is correct. Do you really want to save in EPSG:4326 or rather in a meter based system? 
> 
> What kind of data are you saving? Orthoimages or maps with few colors or black and white? If it is orthoimages, I would use JPEG compression in the Geotiff, otherwise probably deflate/LZW. 
> 
> Then you have to find a meaningful resolution. If you really want to save in EPSG:4326, you have to specify a resolution in decimal degrees. Try with larger values first, such as 0.05 and then, if it is too coarse go to smaller values. 
> 
> About polygonizing raster to vector: this really depends on the content - and I kind of doubt it if you really get meaningful results. Maybe it works with few colors and homogeneous areas. It certainly would not work well for aerial images. Hope it helps,
> Andreas
> 
> Am 07.11.2016 um 22:05 schrieb Juliana Mori: 
> Hi Andreas,
> 
> thanks for your reply.
> 
> I chose layer extent for extensions and current layer for resolution but still doesn´t work. 
> 
> Should I do this in a different way?
> 
> About the bigger question, no, CARTO doesn´t allow uploading geotiffs. What I´ve done so far is polygonizing the rasters in QGis and uploading the converted shapefile to CARTO. As you said WMS can´t be converted into shape, I´m not sure this is going to work at all... won´t I be able to polygonize a raster downloaded from a WMS server?
> 
> All the best, Juliana.
> 
> 2016-11-07 18:44 GMT-02:00 Andreas Neumann <a.neumann at carto.net>:
> 
> Hi Juliana, 
> 
> "Save AS" as a WMS should work fine - but you need to specify a useful extent and resolution (in map units of your projection). Otherwise it probably fails. 
> 
> I just tested it and it works fine. 
> 
> The bigger question is: will CARTO allow to upload larger Geotiff files? Did you check that? 
> 
> Note that WMS are always raster. You can't convert it into a shp file. 
> 
> Andreas
> 
> Am 07.11.2016 um 21:27 schrieb Juliana Mori: 
> 
> Hello,
> 
> I have loaded a wms server to QGis, which is a raster format. As I need to use this in an external aplication (CARTO) which does not support wms, I´m trying to export the server loaded into QGIS through "save as" funcionality. But it´s not working.
> 
> Do you know how I can export the wms loaded to a file (raster or shp)?
> 
> Thanks a lot, Juliana. 
> 
> ps:: I´m working with QGis Essen, 2.14.3
> -- 
> 
> JULIANA MORI 
> 
> www.julianamori.com [2] 
> 
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  -- 

JULIANA MORI 

www.julianamori.com [2] 
+55 11 999653145 [3] 
  -- 

JULIANA MORI 

www.julianamori.com [2] 
+55 11 999653145 [3] 
  -- 

JULIANA MORI 

www.julianamori.com [2] 
+55 11 999653145 [3] 

  -- 

JULIANA MORI 

www.julianamori.com [2] 
+55 11 999653145 

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