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5

Not at all. When you have some data that was digitized at 1:100,000, it excluded smaller features, which were smaller than the Minimum Mappable Area. For example, suppose you are dealing with topographic data.At 1:100,000 you would exclude large streams and trees.These features are visible at 1:24,000, and should be included in such a map. If you just ...


4

Ok, so after a frustrating week, I've actually found a few new things out about QGis. Cheifly, I was still using version 2.2.0 when I posted this question, I've since upgraded to 2.8.1. What follows is a little bit of a tutorial for those folks who might be looking to tackle the same problem. The solution for me was a plug-in called cadinput by Oliver ...


4

You can clean up the scan in Gimp first and make processing a lot easier: Use the 'select by colour' tool and select the map background, adjusting the threshold to give a nice clean selection. Invert the selection, so the lines and points are now selected. Now 'shrink' the selection down Select > Shrink... by enough pixels so that just you points ...


3

Create nice unique id for lines Convert them to 3d using interpolate shape tool Create field fromZ in above. Use field calculator to populate it, parser Python !shape!.firstpoint.z Populate field toZ, using lastpoint.z Join 3d lines back to original, using unique id, select ones where fromZ < toZ Use flip edit TOOL to flip selected. It works for ...


3

You can also use the plugin 'Rectangles Ovals Digitizing' for creating rectangles, circles and ovals. Side note: Just read that the new geometry engine of the coming QGIS 2.10 supports curved geometry types. I am not sure how this would apply for circles.


3

No. You need a Mapbox Commercial Satellite licence. https://www.mapbox.com/tos/#[YmtIyw] You may trace Mapbox-hosted imagery in order to produce derivative vector datasets for non-commercial purposes, and for OpenStreetMap. If you wish to produce derivative vector datasets from imagery for commercial purposes, you must buy a Mapbox Commercial Satellite ...


3

I have had similar issues. One approach I have done is to use the CadInput tool. This tool allows you to draw vectors based on distances, angles, etc. which ensures that when you enter in a new vector, they snap to the point you want. It works with the snapping tolerance that is native within QGIS. https://vimeo.com/85052231


2

Not being able to save the geometry due to a read only attribute windows with a disabled ok button is an issue in QGIS 2.4. The freehand plugin works fine in QGIS 2.6.0 and QGIS 2.8.1.


2

With ArcGIS for Desktop Advanced, you could Convert all depression lines vertices to points (with Feature Vertices to Points) Convert all vertices back to lines (with Points to Line, with the Close Line option checked) Revert the direction of all lines (with Flip Line).


2

A similar function has been introduced recently It requires the possible values to be grouped on the related layer and is slightly more involved in setup. If you have a layer Plots Name class (foreign key to Classes:pk) And a layer Classes pk Type [Agriculture/Forest] Plant [Pines/Olives/Corn/Wheat] You will need to add a new relation in Project ...


2

The easiest way would be the following: enable snappig on the line layer that you are using to digitize digitize the line, but finish your sketch before you close it digitize another line, start digitizing at the end of the previously digitized line (using snapping), finish the line at the start of the previously finished line (using snapping) now select ...


2

Steven already shared a very good walk-through! I just want to add that you could also use the QGIS LecoS plugin (requires active numpy/scipy installation within your QGIS path) for this purpose. Especially for raster basic cleaning and edge extraction purposes. LecoS has a so-called landscape modifier since some time, which applies scipy's erosion ...


2

I'm not sure how well this will work without trying on your specific raster, but a few pointers. I assume from your image you used Threshold in GIMP to give you a binary raster (inside field/outside field) Removing noise You can use GDAL Sieve to remove the 'salt and pepper' noise - those little holes within the fields. You can do this from QGIS (Raster ...


2

Not sure what version of QGIS you are using. I have 2.8.2-Wien. This has advanced digitising tools that allow creation of circles by selection of two points, selection of three points, selection of centre and input radius and selection of a centre and a point. Just ensure that you have the CADDigitize and CadTools plugins loaded to access some good ...


2

Yes, you can definitely use USGS National map ortho-imagery to extract features, using heads-up digitizing methods (HUD.) The trick here is to work within a projected environment using UTM or State Plane as a coordinate system to ensure fidelity. Another consideration should be the age of the image. Ensure you are working with the most current image possible ...


2

Generally speaking, for vector geometry (e.g. roads, buildings, polygons, areas of interest) these features are created by outside contractors that specialize in geospatial data production. However, the tech companies like Google/Apple/Microsoft must also QA/QC the massive datasets for inaccuracies. A lot of this can be done programmatically by their ...


2

First follow this tutorial to convert raster to vector in QGIS. http://manual.linfiniti.com/en/complete_analysis/raster_to_vector.html Next make selections on the shapefile, based on the attribute values of the countries. Finally export the selection.


1

I wouldn't say it's a hopeless task. After all, these aren't random points - you know they are going to form a linear feature. I spent about 10 minutes with FME - using a dataset of a trail sorted into a random order - and think the NeighborPairFinder transformer is your friend here. It works because for each point on the trail you find the two nearest ...


1

I have downgraded my qgis to version 2.0.1, now it works. It seems to be a bug in the new version.


1

Orthoimagery from The National Map is technically already digital data. Regardless, you may conduct manual on-screen digitizing with USGS orthoimagery as a base to trace specific entities such as houses and roads. Bear in mind the coordinate system of imagery and the feature class you are doing your tracing with to ensure they match while tracing. Also, ...


1

If you are new to GIS, I would recommend using Google Earth Pro (free to use, as of a couple months ago). You could draw polygons in two different layers (residential and commercial). If Excel is only needed to calculate the area, you could simply calculate the area with Google Earth.


1

A workaround is to digitize a temporary line starting from the final start/end vertex for creating something that you can snap to. Delete the helper line afterwards. For a proper fix make a feature request and hope that new snapping option would be implemented sooner or later. With OpenJUMP that has succeeded ...


1

Ok, there is definitely a bug, but I found a temporary fix for it... While I was editing, I had snapping turned on. I needed this in order to snap to boundaries, measure a setback, and then start drawing my feature. I turned snapping off after my measurement line was completed, and... QGIS didn't crash! So, if anyone else runs into this issue, this worked ...


1

In 2.8, digitizing a 2-node line is left-left-right click. (Right click ends it without adding another node.) Try this an report back if the auto increment id is still an issue.


1

First, you should confirm that the edited layer is visible(clicked in layers section).You can also check the color set by default by QGIS for new digitized features. If the two are ok and the issue persists you can first digitize the features then edit their attributes later. Hope this helps !!


1

You can achieve your results with a combination of tools and plugins. It's not perfect but it will work Use "Rectangles Ovals Digitizing" plugin to create rectangles. Use "Advanced Digitizing" tools to rotate the rectangles. See Step 29 onwards of this tutorial for the exact workflow. Use "Orthogonal Digitizing" tool from CAD Tools plugin to draw polygons ...


1

Here would be a way to add a new feature to a polygon vector: # reference your layer, such as the active layer lyr = iface.activeLayer() # get the vertexes of your new geometry and add them to a list coordinatePairs = [] coordinatePairs.append(QgsPoint(-80.23, -3.28)) coordinatePairs.append(QgsPoint(-65.58, -4.21)) coordinatePairs.append(QgsPoint(-65.87, ...


1

Thanks very much for pointing me towards CadInput. This got me on a continued hunt and I ended up using another plugin called CADDigitize [ https://hub.qgis.org/projects/caddigitize ]. I was originally confused because this plugin does not provide visual feedback of the snapping. But if you hold down the control key, it will snap the actual nodes when you ...


1

If GISGe's solution works, I'd go for it. Nevertheless, if you still need a solution to remove the holes from polygons, you can just run the union tool and unselect the "gaps allowed" checkbox.


1

There is a company here in town that a large portion of their business is manually digitizing plan and profile sheets for gas and oil companies. Presumably because the CAD files aren't available or it would be just as much work or more to translate them into the desired GIS data structure. I and others I know of frequently digitize field notes and sketches ...



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