March 2012
1 post
3 tags
Python/Tkinter/ArcPy programming notes
This is what we learned (but not necessarily tested on) for using Python with ArcGIS software: Google Doc link
February 2012
4 posts
2 tags
Map algebra, cont'd
I want to make an addendum to the map algebra chat from a previous post…
Apparently the syntax I used is a remnant of previous versions of ArcGIS. Our instructor had taught us the more clumsy one because it’s the way forward. The v10 documentation for the Con tool has a little look to the past when it shows the alternative (old) syntax in a sample expression.
I hope ESRI keeps the...
2 tags
Map of the Slesse Creek Watershed in Chilliwack,...
This is another map, created recently for a class assignment on watershed spatial analysis. This time, I figured I commit fully to producing a proper cartographic map by use of a proper illustration tool. In comes Adobe Illustrator!
Here are some things I did to prepare for exporting to AI:
set colour ramp for the hillshade basemap,
set classified colours of the watershed raster,
edited...
1 tag
GIS as an Information Visualization
There was a presentation assignment we had to do last semester where we each select a GIS topic to present to the rest of the class. I decided to share this since I still receive positive feedback on it from classmates. Click here for a copy of my presentation as well as my talking points.
I think every map maker should have a background in information visualization. Cartographers have some...
2 tags
Some cartographic models I made + a little chat...
Here are some cartographic models I made for my classes. I didn’t like using ModelBuilder from ArcGIS (mainly because I couldn’t figure out how to change the symbol shape for tools), and created these models from Google Docs instead. The UI, aesthetics, and ease of use for Drawing documents actually make them a joy to create.
The first model deals with remote sensed imagery.
In the...
January 2012
1 post
1 tag
SQLPlus: Using substitute column as variable in...
I have a query that I thought I should optimize. It uses an arithmetic operation to calculate a difference in values and a conditional statement to filter out the calculation. The query is this:
SELECT citycode, (pop2001-pop1996)
FROM population
WHERE (pop2001-pop1996) > 10000;
I wondered if I could instead simplify the statement and output to something along the line of...
December 2011
2 posts
Fundamentals of Multimedia
Is there a book I wish I hadn’t sold? Is there a book I miss right now? Yes…
As I was going through the past semester of BCIT’s accelerated GIS program, I kept trying to find a textbook from my BSc. studies. It was for a course that taught image data storage techniques and how to implement them. It was where theories of discrete signal processing were finally applied and I...
2 tags
November 2011
1 post
2 tags
Numeric variable size types: SILFD
This is a reminder to self. I came up with this acronym to memorize the size order of numeric variables supported by ArcGIS. int is included for pronunciability of acronyms. It is actually a short int or long int.
SHORT: 2 bytes INT: 4 bytes LONG: 4 bytes FLOAT: 4 bytes, fractional DOUBLE: 8 bytes, fractional
Ref: http://help.arcgis.com/en/arcgisdesktop/10.0/help/003n/003n0000001m000000.htm
September 2011
2 posts
2 tags
Problem: Attributes table doesn't seem to show all...
Let’s say a polygon was created while correcting topological errors. Double-checking if the polygon really was created, you opened the attribute table window - or had it opened already and refreshed the cache - and see that the number of objects is still the same. You’re sure there was a new polygon created because it’s selectable, you’re on the right layer, the table is...
2 tags
wget a page
wget -v -e robots=off --wait 1 --ask-password --user=[username] -r -p -k -A [extensions list] [url]
ignores robots.txt
prompts password with HTTP Basic Authentication
recursively crawl through accepted linked resources and saves onto local dir
June 2011
1 post
3 tags
FOUND: Photo base map of Vancouver.
Around a month ago, I thought I had to give up finding a suitable base map in which to edit my SHP files with. The problems were many-fold:
free access to data
data of raster layer of aerial, photographic Vancouver
data that QGIS can import
a GIS application that can edit my SHP file
Yesterday, I experimented on Google Map’s My Maps service to edit my SHP file. While I was able to...
April 2011
3 posts
4 tags
Scrobbling radio tunes
This is amazing. A fellow last.fm scrobbler developed a little OSX app to scrobble radio tunes from iTunes: iTunes(Radio)Scrobbler.
The main radio I listen to is FM4 and it prefixes “[artist name] - [song title]” format with the name of their program, eg. “Morningshow: “. Obviously this skews the info to my last.fm library, so I made the following fix for my own use:
In...
6 tags
OSM PBF to PostgreSQL to QGIS
I have a SHP file of a city-level detail which I would like to edit. In order to do that, I’m juggling between uDig and QGIS to compare usability. I’m focusing on QGIS here, because it seems a lot of folks give it props. Here, from beginning to end, is what I did:
I have had no success finding satellite imagery of my city - Vancouver - through searching their list of WMS servers (the...
2 tags
Functional programming in Perl
I’ve been reading CGI::Ajax documentation and came across this example:
use strict;
use CGI::Ajax;
use CGI;
sub evenodd_func {
my $input = shift;
...
}
where the function could also be written as:
my $evenodd_func = sub {
...
};
Awesome.
(Just want to put a disclaimer that I’m only working with Perl in order to fork an app I use.)
March 2011
2 posts
4 tags
MLS accepts XML input parameters to fetch search results. This query URL is taken from a HTTP header read of using their map...
3 tags
2011 GeoDesign Summit: Lauren Rosenshein: The Use... →
The amazing thing is the web UI output shown at the end.
