Re: [Qgis-user] How to get rid of the rest of the World?
how to make a rectangular area of longitude and latitude coordinates that enables to cut away the area not needed in other layers? In QGIS 2.2 (and just about any GIS that has geoprocessing tools) there are two ways to extract data. The first is to clip the data from the existing file using another polygon file: 1. on the manage layers toolbar click New Shapefile Layer; 2. enter info on file geometry (polygon), name, and coordinate system (don't need to worry about attributes); 3. click 'OK; 4. name file and choose storage location; 5. click Save; 6. name of new file appears in 'Layers List; 7. click on name of new file to highlight it; 8. on the digitising toolbar click Toggle Editing (little pencil button); 9. click Add Feature button; 10. click in map window to create your polygon (left click for each corner and right click to finish); 11. click Save Layer Edits button; 12. click 'Toggle Editing button; 13. in menu click Processing... Toolbox; 14. in toolbox (simplified view) search clip; 15. double click geoalgorithms... vector... overlay... clip; 16. input layer is the layer you want to clip (make smaller); 17. clip layer is the polygon you just made; 18. clipped output is what and where you wish; 19. click Run NOTES: -You can turn on any toolbars that you don't see in the menu under Settings... Toolbars -If you load the layer you want to clip into the map window before clipping it means you don't have to navigate to it; you can just pick it from a dropdown. -MAKE SURE THE COORDINATE REFERENCE SYSTEM (CRS) FOR THE PROJECT (Setting... Project Properties... CRS) AND EACH OF THE FILES (input and clip) ARE THE SAME! -If you want to be more accurate with your corners than a quick and dirty hand digitised job then you can import the coordinates for the corners you want using the 'XYtools plugin to import spreadsheet files with xy coordinate fields/columns; make a point file and then snap your polygon file to the points when you create the polygon feature. -You can also create a polygon with accurate coordinates for corners using Python code here: https://code.google.com/p/pyshp/ The second way is to run a SQL query on the attribute table (or manually select the polygons you want to extract) for the polygons you want and then : 1. right click the filename in the layer list; 2. click Save as; 3. name and locate file and choose CRS; 4. click OK. This won't give you a rectangular extent (unless you have unusual data), but will give you exactly the polygons you want. To clip the raster you can use the Toolbox again: Geoalgorithms... Raster - vector... Raster - vector operations... Clip grid with polygon YOU MUST HAVE SAGA INSTALLED ON YOUR MACHINE TO USE THIS TOOL (standard with Osgeo4w install of QGIS) You can also use the command line shell installed when you install FWTools to run gdal_translate to clip rasters - Like so: http://www.surfaces.co.il/clipping-a-raster-with-gdal/ I repeat just want a specified area that easily can be determined by longitude and latitude coordinates. Then use the spreadsheet import or python scripting approaches to create a clipping polygon with the desired coordinates. Using the clip tools this is simple as after you get your clipping polygon created. Cheers, Mike Qgis-user mailing list Qgis-user@.osgeo http://lists.osgeo.org/mailman/listinfo/qgis-user -- View this message in context: http://osgeo-org.1560.x6.nabble.com/How-to-get-rid-of-the-rest-of-the-World-tp5136462p5136667.html Sent from the Quantum GIS - User mailing list archive at Nabble.com. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user
[Qgis-user] How to get rid of the rest of the World?
Hello everyone.. I will be going on a little bit here now.. Wonder how to create a clip/mask layer or do something to the same effect? More specifically, how to make a rectangular area of longitude and latitude coordinates that enables to cut away the area not needed in other layers? Since stuck with a quarter of the World or even the entire World in my little project. This question is for shape file layers mostly, have not gotten to the .tiff yet. They are not global though larger then needed. So a universal solution for both types would be nice. Is there a python console command to do this? Is there a plugin to do this? Is there a online service to create such a layer? Is it possible from within QGIS? Have tried the make a rectangle plugin, it cuts out zero features. Also tried clipping with a layer of not the right shape and it says that they do not have the right projection, even though it looks as they do, and end up with a blank layer. Sure plenty people have this problem, though the forums do not have any clear explanations as I found nothing that really explains, even youtube got one but that is for regional borders. Is there some way of just knocking in the longitude and latitude to do this? Please assist. Do not get why this should be so difficult. Why does not QGIS ask first thing which area of the planet you wish to work on a project? And then just filter out it automatically when you load layer that include more than that? Perhaps this could be a feature of a future release? With hopes for many answers and simple solutions. I repeat just want a specified area that easily can be determined by longitude and latitude coordinates. Yours hopefully.. Marcus ___ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] How to get rid of the rest of the World?
Marcus, I think what you are asking is can you just view the area that you are working on and have QGIS hide or filter out those feature not within the area of concern. From my understanding is no. Well not exactly. My understanding is that shapefiles will allways be processed regardless of whether they are visable. Feature may not be visible if they are outside the view or transparent. You have two simple solutions to this problem. 1. Create a routine to, or manually, clip all the shapefiles in your project based on a reference polygon bounded by your lat/longs. 2. Create a polygon covering the world and punch a hole through it, essentially creating a window bounded by your lat/longs. The polygon can be made opaque/white making it the same as the screen/page or semi-transparent, essentially fading the underlying features (nice effect in reports). On 22/04/14 23:57, kmgkmgkmgkmg . wrote: Hello everyone.. I will be going on a little bit here now.. Wonder how to create a clip/mask layer or do something to the same effect? More specifically, how to make a rectangular area of longitude and latitude coordinates that enables to cut away the area not needed in other layers? Since stuck with a quarter of the World or even the entire World in my little project. This question is for shape file layers mostly, have not gotten to the .tiff yet. They are not global though larger then needed. So a universal solution for both types would be nice. Is there a python console command to do this? Is there a plugin to do this? Is there a online service to create such a layer? Is it possible from within QGIS? Have tried the make a rectangle plugin, it cuts out zero features. Also tried clipping with a layer of not the right shape and it says that they do not have the right projection, even though it looks as they do, and end up with a blank layer. Sure plenty people have this problem, though the forums do not have any clear explanations as I found nothing that really explains, even youtube got one but that is for regional borders. Is there some way of just knocking in the longitude and latitude to do this? Please assist. Do not get why this should be so difficult. Why does not QGIS ask first thing which area of the planet you wish to work on a project? And then just filter out it automatically when you load layer that include more than that? Perhaps this could be a feature of a future release? With hopes for many answers and simple solutions. I repeat just want a specified area that easily can be determined by longitude and latitude coordinates. Yours hopefully.. Marcus ___ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user -- Cheers Simon Simon Cropper - Open Content Creator Free and Open Source Software Workflow Guides Introduction http://www.fossworkflowguides.com GIS Packages http://www.fossworkflowguides.com/gis bash / Pythonhttp://www.fossworkflowguides.com/scripting ___ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] How to get rid of the rest of the World?
Hello Marcus, The feature I believe you are describing is being worked by a few developer, have a look in this pull request: https://github.com/qgis/QGIS/pull/1254 Maybe it lands in QGIS 2.4 :) Alexandre Neto On Tue, Apr 22, 2014 at 2:57 PM, kmgkmgkmgkmg . km.gul...@gmail.com wrote: Hello everyone.. I will be going on a little bit here now.. Wonder how to create a clip/mask layer or do something to the same effect? More specifically, how to make a rectangular area of longitude and latitude coordinates that enables to cut away the area not needed in other layers? Since stuck with a quarter of the World or even the entire World in my little project. This question is for shape file layers mostly, have not gotten to the .tiff yet. They are not global though larger then needed. So a universal solution for both types would be nice. Is there a python console command to do this? Is there a plugin to do this? Is there a online service to create such a layer? Is it possible from within QGIS? Have tried the make a rectangle plugin, it cuts out zero features. Also tried clipping with a layer of not the right shape and it says that they do not have the right projection, even though it looks as they do, and end up with a blank layer. Sure plenty people have this problem, though the forums do not have any clear explanations as I found nothing that really explains, even youtube got one but that is for regional borders. Is there some way of just knocking in the longitude and latitude to do this? Please assist. Do not get why this should be so difficult. Why does not QGIS ask first thing which area of the planet you wish to work on a project? And then just filter out it automatically when you load layer that include more than that? Perhaps this could be a feature of a future release? With hopes for many answers and simple solutions. I repeat just want a specified area that easily can be determined by longitude and latitude coordinates. Yours hopefully.. Marcus ___ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user ___ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] How to get rid of the rest of the World?
I usually make a new vector Layer. Then you can draw or use the numerical vector editor to add a polygon. This polygon can then be used as a clipping mask. Simply having a layer of a given extent isn't enough, you have to have a polygon object in the layer. As for why this isn't the way it already is, well QGIS is not ArcINFO or GRASS where all data in one map are forced into the same projection and you can set an extent property for the analysis. That's a different concept of how to do GIS. One that is not very forgiving to projection on the fly. Thanks, Alex On 04/22/2014 07:24 AM, Simon Cropper wrote: Marcus, I think what you are asking is can you just view the area that you are working on and have QGIS hide or filter out those feature not within the area of concern. From my understanding is no. Well not exactly. My understanding is that shapefiles will allways be processed regardless of whether they are visable. Feature may not be visible if they are outside the view or transparent. You have two simple solutions to this problem. 1. Create a routine to, or manually, clip all the shapefiles in your project based on a reference polygon bounded by your lat/longs. 2. Create a polygon covering the world and punch a hole through it, essentially creating a window bounded by your lat/longs. The polygon can be made opaque/white making it the same as the screen/page or semi-transparent, essentially fading the underlying features (nice effect in reports). On 22/04/14 23:57, kmgkmgkmgkmg . wrote: Hello everyone.. I will be going on a little bit here now.. Wonder how to create a clip/mask layer or do something to the same effect? More specifically, how to make a rectangular area of longitude and latitude coordinates that enables to cut away the area not needed in other layers? Since stuck with a quarter of the World or even the entire World in my little project. This question is for shape file layers mostly, have not gotten to the .tiff yet. They are not global though larger then needed. So a universal solution for both types would be nice. Is there a python console command to do this? Is there a plugin to do this? Is there a online service to create such a layer? Is it possible from within QGIS? Have tried the make a rectangle plugin, it cuts out zero features. Also tried clipping with a layer of not the right shape and it says that they do not have the right projection, even though it looks as they do, and end up with a blank layer. Sure plenty people have this problem, though the forums do not have any clear explanations as I found nothing that really explains, even youtube got one but that is for regional borders. Is there some way of just knocking in the longitude and latitude to do this? Please assist. Do not get why this should be so difficult. Why does not QGIS ask first thing which area of the planet you wish to work on a project? And then just filter out it automatically when you load layer that include more than that? Perhaps this could be a feature of a future release? With hopes for many answers and simple solutions. I repeat just want a specified area that easily can be determined by longitude and latitude coordinates. Yours hopefully.. Marcus ___ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user ___ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user
