The process of converting features on a map or image (either hardcopy or digital) to vector-based data in digital format.

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6
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5answers
2k views

How to Digitize Free Satellite Imagery in QGIS - Alignment issues with Openlayers Plugin

I am trying to digitize OpenLayers data (such as Google satellite imagery) with no success. Whenever I try to move or zoom the canvas the vector layer I digitized loses the position relative to the ...
1
vote
1answer
1k views

How to go with…somewhat complex geological maps in QGIS?

Just a follow-up to this question QGIS: Line to polygon conversion. Not sure do i have to continue there itself... We are currently digitizing a geological map...which has 36 features in total. Some ...
12
votes
3answers
9k views

How to create polygons with straight lines and right angles in QGIS?

I am running QGIS 1.7.0 on Mac OS X 10.6.8. When creating a polygon, how do I do it so that the lines are straight (90, 0 degrees, etc.) and when I create corners they can be right angles? For ...
3
votes
3answers
813 views

“add feature” tool QGIS 2.0 - polygon fill blocks view of what I want to digitize

How can I change the settings on the vector "add feature" tool so the tool fill doesn't block my view of what I want to digitize? This problem popped up after I upgraded to QGIS 2.0 QGIS 2.0 ...
8
votes
4answers
7k views

How to digitize a raster automatically

I have a raster (.sid extension) file. I want to digitize roads automatically in ArcMap, QGIS..etc. Digitizing by hand would be too time consuming. How can i do this ? Thanks
9
votes
3answers
2k views

How can I digitize features on an Y,Z plane in ArcGIS?

How can I geo-reference and digitize features on a Y,Z plane of a vertical cross-section in ArcGIS? The surface coordinate system is NAD 83 UTM 15. This is a simplified version of the question found ...
4
votes
1answer
2k views

Is there a QGIS bezier curve tool?

I'm a recent convert to QGIS but have been confused about the lack of support for drawing curved shapefiles, especially when Arc has almost too many. A lot of the work that our consultancy do is based ...
2
votes
1answer
832 views

“Node tool: could not snap to a segment on the current layer” message

I have a strange issue. Editing a layer with node tool I get always the following message: "Node tool: could not snap to a segment on the current layer." This error happens to me even with a fresh ...
1
vote
1answer
1k views

How to indicate flow of a watershed feature?

While tracing and digitizing rivers, streams, rivulets, etc., is it possible to indicate the direction/flow in the shapefile on QGIS? I'd like to avoid using map labels. Ideally, when done tracing, I ...
6
votes
2answers
8k views

snapping polygons and lines

I recently downloaded QGIS on a Mac OSX 10.7.4 (lion) and purchased a master map shape file, of a particular area. I am trying to divide it into polygons following features on the master map vector ...
3
votes
2answers
2k views

Figuring out map scale when you know the spatial resolution of a Satellite Image?

I'm interested in figuring out how map scale and satellite pixel size (spatial resolution) are related. For example the TM or ETM+ has roughly 30m ground resolution, then, what could be the finest ...
6
votes
2answers
1k views

How to digitize building footprints with orthogonal edges?

Using QGIS, I am trying to digitize an old raster map, and because I ultimately want to load these 2d layers into sketch-up to turn into 3D models, I need everything to be square. Here's a sample of ...
5
votes
0answers
884 views

Does QGIS have these CAD editing functions? [closed]

I tried QGIS for the fist time today and it seems quite capable for the task that I have in mind. However, I really miss some basic editing functionality from another GIS software that I have to use ...
2
votes
2answers
301 views

How to automatically convert dots on paper maps to vector points?

I have several paper maps with dots that I need to convert to vector points. I was hoping to get some suggestions on how to accomplish this without recreating each and every point by hand. I know ...
7
votes
1answer
1k views

Is there a way to automatically snap loose points of lines to close by vertices with Quantum GIS?

I have a vector layer of lines that were drawn with the snapping option off. I need to have them snapped but, there are hundreds of lines. Is there any solution to do this automatically or semi-...
3
votes
0answers
104 views

How to digitize 90 degree angles? [duplicate]

Possible Duplicate: How to create polygons with straight lines and right angles in QGIS? In QGIS 1.8 is there a way to digitize buildings etc. with perfect 90-degree angles, Or, edit a polygon ...
3
votes
2answers
170 views

I am unable to draw a shape layer

When I add a new shape layer or want to edit an existing one, nothing is happening. I even don't see the dots where I'm clicking. Maybe the problem is I deleted some layers (by opening the .qgs as a ...
2
votes
2answers
177 views

Digitized Shapefile manually using wrong projection: how to fix it?

I have a raster in correct projection. I used shapefiles, and marked objects (manually), but I found out that my vector layers have different projection, so they have different size and position. Is ...
2
votes
1answer
2k views

When I finish drawing a polygon, it disappears again (although appearing in my attribute table)

I'm working with Quantum GIS at this moment. And as the title says, when I finish drawing a polygon, it disappears again. The new object does appear in my attribute table and in the legend/'filling of ...
2
votes
1answer
286 views

How to find the projection of an image?

Instead of georeferencing the image and deforming it, I'm trying to find the projection used by the author of the image. I've got tens of these distribution maps to digitize. The idea is to avoid ...
1
vote
1answer
98 views

Digitized Map To Scale

Is it perfectly acceptable to produce a map at a scale of 1:24,000 from a database that was digitized from a 1:100,000 scale source map?
1
vote
1answer
227 views

QGIS: Line to polygon conversion

Currently we are working in a geological project..in which all the Contacts, Linear & some other geological features have to be captured. The thing is most of the features have to be Captured as ...
1
vote
1answer
686 views

Can I resume (continue) digitizing a polygon feature from any vertex?

When I digitize in ArcMap with a Wacom tablet and a pen I often accidentally double click and finish my sketch. More often then not the accidentally finished sketch crosses itself. I would like to ...