Tag Info

Hot answers tagged

7

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, ...


5

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 ...


5

Although i hate giving link-only answers your question literally calls for it. If you have absolutely no idea how to start you should definitely read some tutorials first. The purpose of this site is to help you with GIS problems and not to teach you how to work with GIS-software! IMHO this requires to take ether a professional course or a lot of spare time ...


5

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 Sextant ...


5

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. ...


4

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 ...


3

The result of the interpolation that you digitized is represented in classes instead of continuous values. Therefore each color represent a interval of values, something like: < 100 100 to 250 250 to 500 > 500 (Note that the limits could be inclusive or exclusive) Now, if you plan to do some algebra analysis with it, classes and categories might not ...


3

Under Settings > Options > Digitizing, Find the "Rubberband" setting, Then "Line Colour" and adjust the "Alpha Channel" on the colour chooser. I find that an Alpha value of 50 gives a nice level of transparency but of course you can tweak it as you desire:


2

I have figured this out. My project included tracing multiple river islands and sandbars, and 9/10 times my painstaking sketches disappeared using the auto-complete freehand or polygon tools. I noticed that the 1 polygon out of 10 that was created was a bit messy, i.e. the last line or point crossed the initial line or point where I started the shape. It ...


2

Something to keep in mind is that portolan chart navigation maps like Piri Reis don't a have coordinate system, rather they are several different local coordinate systems munged together -- each one of the rosettas or compass rose like symbols is a projection source of origin, loosely speaking. So you can't just georeference the image in the usual GIS way ...


2

There is a raster version of the Map You can digitise from this source for personal use. KMZ http://www.gearthhacks.com/dlfile12068/Piri-Reis-Map.htm


2

This is an issue that you'll get any time you digitize based on aerial/ortho photography. Aerial photography, even if it's ortho-rectified, will have varying levels of horizontal accuracy based on what equipment and elevation model were used. I'll bet that your two sets of imagery were compiled and released by two completely different entities (ie. You ...


2

I assume you need to produce a paper map because the term "scale" nowadays makes sense only when talking about paper maps. There is a formula that calculates the scale of the paper map: 1/x = 1 / (30 m/pixel × 4000 pixels/m) = 1:120,000 So, you would produce a map with a scale of a 1:120 000 using your 30 m images. For more details see: ...


2

First, if you don't have source imagery to work from you'll need to acquire a georeferenced orthophoto. If you're in the US you can try using the NAIP photos. NAIP photos are leaf-on photos, and usually 1 meter resolution. Next, once you have your imagery to work from set your project's CRS to match the photo's. Then create a shapefile and use the ...


2

You might like to have a look at this document, which shows an example of using the Polygonizer to make a geological map. http://confound.me.uk/maps/ppv4.pdf‎ After some recent problems, in my version of QGIS (2.3.0-Master, from Ubuntugis) the Polygonizer is now working again. Search for 'Polygonize' in the Processing Toolbox. N.


1

@Mapperz suggested I configure my tablet not to response to double click. I tried doing this but the features were non-responsive. It seems that the Pen and Touch and default windows tablet features and services are taking over some of the Wacom Intuos functionality. After I turned of the Table PC Input Services and then Tablet PC Component Features and ...


1

You can snap a line to itself, but only after saving. My workaround is to digitize the line, but set the last point a bit offset to the first point, then save, and then move the last point to the first. As a consequnce, I start digitizing a new closed line with a point that is already created by another adjacent polygon if possible.


1

Go to Settings -> Options. In the Options menu go to the Digitizing tab, then adjust your rubberband color. Drop your alpha channel value down, by default it is 200, the lower it is set the more transparent your digitized polygon will be as you build it. For me 50 was a good setting. If you set it too low you won't see anything at all. When I was ...


1

I think you ran into this problem: http://hub.qgis.org/issues/6822. See also How to Digitize Free Satellite Imagery in QGIS? Only solution available is to use bing imagery instead of Google, or digitize in Google Earth, export that as kml and use this in QGIS.



Only top voted, non community-wiki answers of a minimum length are eligible