Hot answers tagged jpg
9
There is no direct route to convert an image into a shapefile format. Your jpg map has no spatial reference. You can load it into arcmap but it won't know where to put it. In order to tell arcmap where it belongs in space you have to provide geographic reference points, hence the term 'georeferencing'.
In ArcGIS this is done via the Georeferencing ...
5
(1) and (2) are possible with eVis plugin (Documentation).
Ad (3): You should be able to use Field Calculator to add the path to the filenames you already in attribute table. Field calculator is described here: http://www.qgis.org/wiki/Calculating_field_values. You can use + operator to concatenate strings.
4
Yes there is, but before that, what software do you have available? To georeference a non georeferenced jpeg you will need to know/have one of two sources of information.
1) Access to vector or raster data that covers the same geographical area in the jpeg
2) Knowledge of the geographical extents of the jpeg (ie: Lat/Long cooridinates or UTM coordinates)
...
4
When you save your JPEG in GIMP, expand the 'Advanced Options' when the 'Export as JPEG' dialog box comes up. Un-check the 'Progressive' box and then click 'Export'. Your JPEG is then readable in QGIS.
"Progressive" changes the encoding to display the image at increasingly higher quality levels until the image is fully loaded. QGIS is expecting standard ...
3
You need to include empty quotes for parameters you aren't changing. Since resolution is the 6th parameter, you shouldn't place it directly after parameter 2 (out_jpeg). The empty quotes are place markers.
Example: arcpy.mapping.ExportToJPEG(mxd, project, "", "", "", resolution = 200)
You don't need to put quotes in for parameters after the last one you ...
3
I suspect that there are a great number of factors that go into the choice of image format and compression scheme:
Image dimensions
Bit depth
Image complexity (images with large areas of similar colors may actually compress better by a lossless codec than a lossy codec, and some codecs handle complex, detailed areas better than others)
Multi-band support ...
3
How about using GDAL? It is available via FWTools (easier install) on Windows, via apt-get on Ubuntu, and via a binary for OSX.
Once you have GDAL just go ahead and use:
gdal_translate -of JP2OpenJPEG <input> <output>
or
gdal_translate -of JPEG2000 <input> <output>
The above command uses the built in JP2 format conversion. ...
3
QGIS has a plugin called "Photo2Shape" that will convert the geotagged coordinates of the photo into a shapefile.
You can then use the "eVis" plugin to set up hotlinks to the photos themselves, and launch a photo viewer by clicking on the attribute field.
3
I had posted a question on creating images from vector data that you might find useful. The accepted answer, the combination of shapely, ogr, matplotlib, and numpy seems like it would work nicely for you.
2
Here is a link to the QGIS forum reporting something similar in terms of band combinations. This article is referring to rasters generated in GRASS but there maybe some similarities.
Another trick that has worked for me in the past. Make sure the .jpg file has an associated world file .jgw and a projection file .prj. These can be generated from exporting ...
2
It seems QGIS doesn't set the correct band in the jpg raster. You can fix this by double clicking your raster layer and changing the bands
Where it says Red, Green, Blue Band they must all be the right color bands from the jpg. Change Green band drop down to Band 2 and Blue band drop down to Band 3
2
The simplest way would be to call gdal_rasterize using subprocess.call(), but I suspect it doesn't do any interpolation so it would alias to the point of illegibility if you generated a thumbnail-sized image straight from the data. So you should generate a "reasonably sized"* temporary image and use the Python image library to scale it to the size you want.
...
1
if you want to try an opensource solution for georeferencing your image with some GCPs (Ground Control Points), you can go with this way.
firstly use your gcps.
gdal_translate -of GTiff -gcp 0 0 31.7431761644 35.1680410195 -gcp 3527 0
31.7493769674 35.1784535489 -gcp 3527 2492 31.7431011291 35.1784951643
-gcp 0 2494 31.7431761644 ...
1
To georeference an image, you should know the lat/long values of at least 3 locations on the image. The more the better. These are called GCPs (Ground Control Points). Once you have the GCPs, you can transform the image to fit in a real world coordinate system (like lat/long). Many times you can get coordinates from the markings on the scanned map image ...
1
The method here works in ArcGIS10.1. Besides the jpg map, you also need another layer: a projected counties map. Steps include:
1. Georeference the jpg to the projected coordinate system of the projected counties
2. create a new vector with the same projected coordinate system in ArcCatolog
3. use editor to create polygon for the vector by taking the jpg as ...
1
Custom Maps created by Marko Teittinen [This app currently has 99 Five Stars out of 138 reviews]
Use almost any map image as offline GPS map.
Custom Maps makes it easy to create GPS maps from map images, and those maps can be used anywhere, even when you have no data signal for your Android device (it works on both phones and tablets).
Custom Maps can use ...
1
If it is ok for you to get cells that have an engineering link attached, than you will find a useful and free little tool on my website. http://www.centauron.de/site/produkte/gpsphotocell/allgemein.dot?com.dotmarketing.htmlpage.language=1
1
Blah238 offered some great considerations. Here are a couple more.
Some of the wavelet compression formats require additional costs to create images. ECW and MrSID are proprietary formats, so you typically have to pay for extra software, a plugin to your software, or a licensing fee in order to create images in those formats. JPEG2000 is an ISO standard ...
1
Just for the sake of completeness - mapserver can also render good looking maps from a range of base data, on commandline using the shp2img utility. Again, you will need to decide on a very generic, very simple style that fits your purposes.
1
Hello Michael(it sounds like Knigth rider..jejejeje)
You already has the procedure to rotate, it is quite easy...then to scale the map you can use somethig like this:
var p = this.CurrentContentView;
if (p != null)
{
var currentExtent = new Envelope();
var newExtent = new Envelope();
var newPoly = new ...
1
QGIS also has an android port, so I suggest you give that a try. During this year's GSOC, it is being improved even further for a more native feel. It requires at least android 2.3 and isn't as resource efficient as a dedicated solution would be though.
1
Mapnik and gdal_rasterize are good options. I usually create a simple mapfile styled however I want and then use Mapserver's shp2img executable. There are good tutorials on creating mapfiles.
1
What is the bigger picture problem you are trying to solve?
Maybe you want to have geolocated images as a starting point, and let that be the basis for the spatial catalogue?
see http://www.qgis.org/wiki/Creating_geo-referenced_photos_for_display_in_QGIS
1
If you have access to GDAL, you could use something like:
gdalbuildvrt dike.vrt *.tif
python gdal_retile.py -of jpeg -levels 1 -ps 1024 1024 -targetDir dike_output dike.vrt
If you use the latest Quantum GIS, these commands are on the Raster menu.
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