QGIS

Field Work and a Phone and QGIS

rjhale · Mar 21, 2013 ·

Sorry for the quiet – had a lot going. So much so – let me start off here: Greetings from the US Virgin Islands.

There’s a lot to discuss and let me start off with Field Work. Yesterday I found myself and my handy coworker Zac roaming Charlotte Amalie. I also am in the possession of a new phone. A Google Nexus 4. We were trying a couple of things. One of which turned into Geotagging pics. You can with (I assume) every android phone (and Iphone) embed your lattitude and longitude into a pic. So that’s what I did. I ended up shooting about 20 pics and a few scenic tourist shots (above). I came back and the plan was to rip them into a shapefile. I think I even uttered that standard phrase of GIS Professionals everywhere “Well – I’ll just write a script to do this.”. Well – I’ve got work to do and script writing is for fun – so here is what I did.

Open QGIS
Download the Photo2shape plugin
Download the pics from the phone to a directory
Run Photo2shape

At the end I had a shapefile with the photo path and photo filename. What was nice I ended up with (red dots).

The Orange line is a different story. Every photo has a recorded location and the reported accuracy of the phone is 9 feet. I’ve noticed that with this phone GPS Status bottoms out there. So I’m guessing this is a software lock or something – because the points when matched to NAIP/Google are pretty close to what was expected. I know – I’m mixing all sorts of accuracies but that’s what I have to check it against. Three meters in general isn’t great – but for what we’re doing it’s pretty good.

Next up – Hyperlinking on QGIS……..

Decoding Sids

rjhale · Jan 7, 2013 ·

Imagery. It’s a pain..or it used to be. I had the fun of being on the “cutting edge” of scanning in my old job. We flew a lot of photography, we ended up buying at least two different scanners, and we started creating out own orthoimagery. It was painful. We would decide on a resolution that balanced file size with practicality. Yes – I would like this at 1000 DPI but I’m only going to get it at 300 DPI. At some point we purchased a Mr Sid license. That relieved a lot of the pain as we were able to ortho and compress a quad sized block of imagery. Coupled with portable hard drives and we were rocking and rolling until someone dropped one.

Flash forward to now and I’m sitting with close to 2 terrabytes of space on my workstation. A lot of my imagery is brought in through various services. What isn’t brought in I download and stick on a portable hard drive and take with me to client locations.

This weekend I hit a bit of a problem. I had Mr Sid compressed NAIP and I needed to use it on my linux workstation – except I hadn’t compiled sod support into my workstation. So I did some investigating and came to a fairly elegant 15 minute solution.

1.Downloaded the Lizardtech tools and utilities and decided to decompress the sid image. It comes in both windows and linux flavors.

./mrsidgeodecode -wf -i input.sid -o output.tif

2. Use GDAL to then jpeg compress and tile the tiff

gdal_translate -of GTiff -co “TILED=YES” -co COMPRESS=JPEG input.tif output_tiled.tif

3. Use GDAL to then Build pyramid layers internal to the image.

gdaladdo -r nearest output_tiled.tif 2 4 6 8 16 32

So exactly what happend? Well – this did:

File	File Size
Original Mr. Sid File	402310123
Uncompressed Mr. Sid	6035447974
Jpeg compressed	591536492
Pyramid layers built	1033756302

So the file went from approximately 400 Mb to 1 GB in 15 minutes – that’s more or less a 2.5 times increase in size. It also displays pretty fast in QGIS and ArcGIS. ArcGIS appears to be reading the internal pyramids because it didn’t want to build any when added. Overall I think the display is a bit faster than the original Sid. I’m not the first to talk about this wizardry.

The point…well. I don’t much care for proprietary compression anymore (I’m looking at you ecw too). The imagery is now more “functional” for me – I can use it where ever. Does it justify decompressing my stash of imagery? Probably not. Should you think about this before you start dealing with imagery? Yes. Tif is a standard. Yes – Sid makes your life easier but you really need to understand you are essentially “locking” your imagery up to an extent.

For all of these steps – add the sid to ArcGIS and right click and export data – you skip the decompression portion with the sid utilities. You get close to the same file size as I did with jpeg compressed.

Anyway – problem solved this go around. Think. Learn.

Updated Training News for January 2013

rjhale · Jan 2, 2013 ·

So I had to move two classes back due to some unforeseen issues coming up – so I moved them back a couple of weeks. Sorry – My news years resolution was to not move classes – and here I go two days in moving stuff around.

January 25th 2013
Introduction to Quantum GIS – Price $350 per person.
This one day class is an introduction to Quantum GIS. Quantum GIS is a user friendly Open Source GIS Package released under the GNU General Public License. It runs under Linux, Unix, Mac OSX and Windows and supports multiple raster and vector formats. Students should be able to navigate and install the software and use it when needed and integrate it into current work flow.

January 22th 2013
Introduction to Model Builder – Price $350 per person
his one day class provides an Introduction to ESRI’s Model Builder application found within the ArcGIS Desktop Software. ModelBuilder is an application you use to create, edit, and manage models. Models are work flows that string together sequences of geoprocessing tools, feeding the output of one tool into another tool as input. ModelBuilder can also be thought of as a visual programming language for building workflows.

Introduction to QGIS Class January 11th 2013

rjhale · Dec 10, 2012 ·

….and I’m doing it again. The Introduction to QGIS class will be held on January 11th 2013.

This one day class will cover the basics of QGIS and should give you a good idea of the capabilities and possibilities with the software.

Subjects Covered:

Overview of GIS
Introduction to Quantum GIS
Vector Data
Raster Data
Plugins
Fields and Attribution
Creating Data
Map Layout

As always you get 1 year of Level III support. Part of the class fees also get contributed back – so while you are learning you are also helping further the development of the software.

Class Price:$350 dollars.
Location: Chattanooga TN
Date January 11th 2013

Contact me (rjhale@northrivergeographic.com) for more information.

GIS Bubble

rjhale · Nov 26, 2012 ·

I spent the day working and thinking. I saw this earlier last week and it popped up again either on twitter, facebook, or somewhere:

It’s an interesting look at Google Maps and how it got to where it is now. Plus some nifty editing tools. Of course if you watch that – then you must watch this:

Yeah – it’s two separate things. Search and Mapping – but not really. It’s why I like working on OSM – I map what I want. You can do the same with Google – but I do worry about the filter bubble with Google Maps. Things can go wrong. Things can be ignored. It’s not anything inherent in google maps – I think it’s more the way we perceive things. You get used to one thing – be it Google or ESRI and you develop blinders. Hence my new love affair with Quantum GIS, PostGIS, and DuckDuckGO.

Change is good. Change up your GIS. Change up the way you look at maps. Stand on your head if you need to – it helps.