40

In Settings / Options / Digitizing, you can define the distance radius in pixel or map units to snap to other points. And in Settings / Snapping options you can choose which layers can be used for snapping. The only thing that does not work is snapping to the points of a line or polygon you are just creating. Software version: QGIS 2.18.20


22

There is a Shape Digitizing toolbar in which has an option to add rectangle using different methods: To show the toolbar, right-click the main menu and select Shape Digitizing toolbar I am using QGIS 3.4.


20

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 Dlang, I'd installed this quite sometime ago, but never actually looked at what it did. Then I ...


17

For QGIS 3: See ahmadhanb's answer. Original answer: Check the CadTools plugin. It offers orthogonal line tools. Here's what the help says:


15

You should be able to use the Arrow At End symbol from the Symbol Selector to show the digitised direction of polylines.


11

The QGIS solution in Mapperz' reply is just a simple raster to vector conversion and has no edge detection, so I doubt it would be very effective for this use-case. It will give you polygons per pixel value and for a photo that could result in almost a polygon per pixel! A better option in QGIS might be to use the Edge Extraction feature in the Sextante ...


10

There is no need to manually digitize all the OSM Maps. According to the OSM website OpenStreetMap is a map of the world, created by people like you and free to use under an open license. So you are able to use the underlying data in all the maps, Simply download what you want to use, following the steps in this guide or this one.


9

I would suggest talking to your local university or college. I work in a Geography department at a university in the geospatial data centre and we are doing a similar project with aerial photography for our local city. Universities can hire students, or make it apart of the class work. Many profs like the chance to tie their teaching to real world ...


9

I tried the suggested solutions but found the CADTools plug-in a bit too complicated to get a quick hang of it. Besides, this is a rather simple task. Instead I found the plug-in Rectangles Ovals Digitizing by Pavol Kapusta. The name is rather self explanatory and it works excellently. You can draw shapes from centre or by extent.


9

Since you mentioned that are you doing network analysis, I recommend assigning the symbology for your road edges within the network dataset layer in the TOC instead. You are on ArcGIS 10.2, so here are the steps: Add the network dataset into the ArcMap TOC. Open the Layer Properties dialog box by double-clicking the network dataset layer in the ArcMap table ...


9

The v.split.length function from GRASS should do exactly what you want by splitting the line into equal segments defined by the user without the need for a point layer. Here's a simple example of a straight line (it also works on non-straight and multiple lines): I added a column to calculate its length using $length in the expression: Using the v.split....


9

there's three steps to this buffer (as mentioned by DPSSpatial). This draws an outline a fixed distance away from your blocks. Find this in Vector > Geoprocessing tools > Fixed distance buffer make a line layer from the buffer layer (Vector > Geometry Tools > Polygons to Lines). This is needed for the next step chainage (specifically the qchainage plugin) ...


8

There are many options for you in ArcGIS, however I would stay open to open-source solutions too. You can purchase an extension for ArcGIS called Feature Analyst, which uses a feature extraction algorithm. Otherwise, try Iso Cluster Unsupervised Classification (Spatial Analyst) on 4-band DOQ's (Earth Explorer). Once you find the right recipe for ...


8

The Reshape Feature Tool can be helpful for this job. Draw the new common border of the polygons (here in red color):


8

While I agree that there are much better tools to accomplish this task, I'll give it a go just for the sake of answering the question, as cumbersome as it may be. It is still going to take a good deal of manual effort, but at least you can knock out multiple doorways at once this way. Basically, you can create point features wherever your doors are, ...


7

I agree with Alice and Stephen. If they will not share the data, then you are out of luck. You could argue that if they had not disabled directory browsing of their REST endpoints, then whats to stop you from hitting the unsecure service endpoints with a query like this to pull back the points your after (also with the choice of asking for them to be ...


7

ArcMap (10.2) Use ArcScan http://resources.arcgis.com/en/help/main/10.2/index.html#//000w00000001000000 but you have to change you image to 8 bit black and white for automatic vectorisation. Note lots of images require clean-up this can be the time consuming component. http://resources.arcgis.com/en/help/main/10.2/index.html#/...


7

As gene mentioned, there is a Spline plugin to digitize curves. Control is limited but it might be a start. Check the plugin settings and adjust the tolerance value to fit your layer CRS and resolution, especially if the CRS is EPSG:4326).


7

I spent a while trying to figure this out too. The button is found in the QgisInterface class. # Find the layer to edit layer = qgis.utils.iface.activeLayer() layer.startEditing() # Implement the Add Feature button qgis.utils.iface.actionAddFeature().trigger() Then add the features you wish to add to the layer.


7

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 ...


7

I'm assuming you want to automatically populate the field with the date at which the feature was edited - apologies if this is not correct. Create the shapefile and add a field in the attribute table in which to store the date - you should be able to specify "date" as the type of input. Add the shapefile into QGIS and then open its properties. Under the ...


7

One method is to use a virtual field which would automatically number your points using the $id expression (or whatever expression you prefer): Note that you will need to save a project file for this as virtual fields are saved in the .qgs file and not in the shapefile itself (but you can re-save the shapefile as a new one using the Save As... option which ...


7

Yes using s will enable/disable snapping.


7

In QGIS, this feature is called Topological Editing. In the Snapping Toolbar, enable topological editing. With topological editing enabled, when you use the Vertex Tool to move a vertex on one polygon, the same vertex on an adjacent polygon will also be moved, thus keeping the shared boundary.


6

You can chose between CAD Tools plugin which is more complex and more powerful, or Rectangles ovals digitizing plugin. After installing the plugin you may have trouble to locate the plugin tool icon or buttons. Look for the plugin tool icons in the toolbars, they are probably in grey color.


6

Maybe the answers to this question are helpful: How to simplify a routable network? I used GRASS v.clean in the end.


6

the CadTools plugin should do what you want. there is also an tutorial: http://www.catais.org/qgis/cadtools/ (especially look under "orthogonal digitzing")


6

This is a classification problem which is best suited to methods outside of ArcMap. Our brains have a very easy time interpreting collections of pixels and assembling them into meaningful objects such as roads. However, these tasks are much more difficult for a computer and require classification algorithms. ArcMap has useful pixel-based classifiers (...


6

Yes, manual digitization is slow. There's a reason why scanning and raster-to-vector processing has replaced digitizing in major paper map conversion efforts. Twenty-five years ago, half of Esri's employees toiled at 4-hour shifts on digitizer boards or worked at QC tasks reviewing data collection. Now there may be a few large boards left, but they're ...


6

What you are looking for is doing a snapping operation, which is a very common task in a GIS software. Simply, go to Settings >> Snapping Options... and set where to apply the snapping and a custom tolerance. For example: In this way, when you will try to digitize a new point, QGIS will automatically snap it to the nearest vertex (from another layer) ...


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