3,956 reputation
33381
bio website elegantdesigns.ca
location Fredericton, Canada
age 32
visits member for 4 years, 5 months
seen 42 mins ago
GIS, Transportation, Civil Engineer in New Brunswick Canada. I'm interested in using FOSS, python, QGIS, PostGIS, GRASS, and QT to develop open source engineering applications

Nov
23
revised Method to shade or overlay a raster map to reflect time of day and ambient light
edited title
Nov
23
comment Vehicle travel data for the USA
I was wondering, were you able to get the data you needed?
Nov
23
revised Method to shade or overlay a raster map to reflect time of day and ambient light
added 392 characters in body
Nov
23
asked Method to shade or overlay a raster map to reflect time of day and ambient light
Nov
20
answered Advice for someone considering a career in GIS (without software development)?
Nov
19
comment Dealing with bridges and tunnels when modeling raster least cost paths?
@julie - WRT (1) As long as the peds are not trespassing, you might not want to build a model that encourages cross cutting even if it is the existing scenario. (2) There is prob. a way to grab centerlines from gaps in a polygon layer (new question?). Modelling wise, I would use regular road data and remove the edges with no sidewalks. I'll add trail data and manually trace whatever doesn't exist. Where roads and trails meet I'd create dummy nodes. The model would favours trails, roads, roads with no sidewalk, and then raster based data such that the route doesn't infringe anyone's property.
Nov
18
comment How to union polygons with common ID in QGIS?
A follow up question; how do you ensure that the boundaries matchup nicely after the dissolve? from experience, I find that I have to go back and remove or redissolve polygons
Nov
18
comment How to union polygons with common ID in QGIS?
I realize you're new to this site and thanks for posting the question; however, the posts are reserved usually for answers, any thanks or additional information could be added to the original posts. Specific comments to a post could be added under each post. Don't forget to accept an answer if it works for you, and feel free to update your question or ask the users for more clarification. Cheers :)
Nov
18
revised How to union polygons with common ID in QGIS?
Fixed up the formatting but I did not correct grammar or spelling.
Nov
15
comment How can I optimize pgrouting for speed?
Just curious have you looked at any Mode choice models? We use the centroids to build slimmed down version of the network, and then we optimize reroute based on it. Mind you, we use this exercise in planning and predicting traffic rather than in operations
Nov
15
comment How can I optimize pgrouting for speed?
Another option would be to build an O/D matrix (origin/destination matrix). This is a technique we use in traffic engineering. split the network into zones, so let's say a large city could have 100 zones. Each zone would have a dummy centroid. Connect the centroid to your network via a dummy link. Then you can remodel your whole network as 100 x 100 trips (10,000 trips in total). When a user does a search, pgrouting has to find a route closed to the centroid or dummy link on the origin and destination side.
Nov
15
comment How can I optimize pgrouting for speed?
I'm not a pgrouting expert, but can you cache results, for example, if you know a common sub route is always used, can you precache it? therefore, you have to do less searches? Also, van you limit searches to Arterials and collectors?
Nov
14
comment Which is the best way to create a polygon with the extents of a raster file in QGIS?
I think this is a better example from the pyqgis cookbook. If you get the extents, you can use this to create the vector bound
Nov
14
comment Which is the best way to create a polygon with the extents of a raster file in QGIS?
I'm not versed with the QGIS API, but would this help?
Nov
13
comment Nearest Neighbor Grouped Selection in QGIS
@whuber this is awesome
Nov
5
comment Where can I find city area data for the US?
I'm on my way out but check out the US Census, and Tiger, also google should have plenty of answers, but try the dot gov websites first
Nov
2
awarded  Notable Question
Oct
24
comment What is the most annoying fact about the GIS market/industry?
What's worse are proprietary spatial formats of companies that don't exist anymore
Oct
24
awarded  Popular Question
Oct
21
comment Projection Decision
Will you be using a js client like Openlayers or Google maps api?