ArcMap

How to determine the #GIS #raster #resolution and #calculate #area

Here is a video on how to determine the raster resolution and calculate area. This video was made in response to Youtube +cojut who posed an interesting comment that you cannot use “calculate geometry” in raster, as one would in polygons. That is a true statement, in fact, to do so can be done by deriving the raster cell resolution and counting the number of “data”-containing cells. Enjoy.

Happy GIS-ing

Advertisements

Using #GIS #Model #Builder to correct #projection and #convert #polygon to #raster

When you have finally gotten used to converting data layers, another feature in ESRI’s tools box is the model builder. This tool allows you to actually employee a number of steps all at once, kind of like a batch process. It’s a bit trick at first, but when you get the hang of it, the Model Builder process flow diagram is a great thing to share with other collaborators so that everyone processes the data the same way. Have a look at my 3-part video.

Still want more information? Well there are a number of resources you can look up online and in print. Here’s one from ESRI press:

Getting to Know ArcGIS ModelBuilder by David W. Allen

Happy GIS-ing!

#GIS #Suitability #analysis using #raster, to identify #suitable residential #areas

Ever want to do a non-bias analysis to determine suitability? Well here’s a tutorial on how to do it.

Disclaimer: My perspective of non-bias is using well-researched numbers. In this tutorial, the numbers are not researched and are just automatically assigned for simplicity. I’ll leave the weighting research to you!

So let me start by introducing what my objective in this video. I wanted to determine a suitability residential location on the basis of access to ambulance an fire stations (in case of emergency). I wanted to identify bikeways because there’s a growing trend to go to bikes because of the traffic jams and constructions on the LRT transit system. I also wanted to find something close to parks because in a city core, parks are very relaxing.

For your convenience, here is a link of the datasets that were used at the time of the video (note the links may be updated). If the links are broken, help me out and place a link in the comment section for other users please (and thank you!).

Ambulance station: http://www1.toronto.ca/wps/portal/contentonly?vgnextoid=93f91c98d2b6d310VgnVCM10000071d60f89RCRD&vgnextchannel=1a66e03bb8d1e310VgnVCM10000071d60f89RCRD
Bikeways: http://www1.toronto.ca/wps/portal/contentonly?vgnextoid=9ecd5f9cd70bb210VgnVCM1000003dd60f89RCRD&vgnextchannel=1a66e03bb8d1e310VgnVCM10000071d60f89RCRD
Fire Stations: http://www1.toronto.ca/wps/portal/contentonly?vgnextoid=373ef5f39ad5e210VgnVCM1000003dd60f89RCRD&vgnextchannel=1a66e03bb8d1e310VgnVCM10000071d60f89RCRD
Parks: http://www1.toronto.ca/wps/portal/contentonly?vgnextoid=da6389fe9c18b210VgnVCM1000003dd60f89RCRD&vgnextchannel=1a66e03bb8d1e310VgnVCM10000071d60f89RCRD

So in the first part of this 5-part series, I start of with showing how to download the datasets. When you are downloading the datasets, it is important to get a copy of the metadata so when you do your report or school project, you have access to all the details on the datasets. Typically these datasets will update occasionally.

After downloading the datasets, you want to make sure your projection is set to UTM. In this Part 2, we do the projection correction. If you’re new to correction projections, I have a number of videos that actual explain projections using a Batch Correction from WGS 1984 to UTM NAD 1983 Zone 17 and a Reporjection WGS 1984 to UTM NAD Zone 17 with Geographic Transformation Basics.  Feel free to check these tutorials out.

You’ll notice in Part 3, we apply the Euclid Distance function and we’ve also reclassified the datasets. Notice how we are suddenly working with raster datasets.

In Part 4, after reclassifying your datasets, its time to Raster Calculate!

In Part 5, we end the tutorial with a bit of post-processing. Please remember, there are a number of ways to post-process your output. This is just one way.

If you’re looking for more information on suitability analysis, there are a number of online and print material you can use. Here are some:
The Esri Guide to GIS Analysis, Volume 3: Modeling Suitability, Movement, and Interaction by Andy Mitchell

A GIS analysis of suitability for construction aggregate recycling sites using regional transportation network and population density features [An article from: Resources, Conservation & Recycling] by G.R. Robinson

GIS-based Land Suitability Analysis: Recreational Facilities planning by Imtiaz Ahmed Chandio

How to download a #GIS #orthophoto #image using #Vancouver #Open #Data

Ever have one of those late GIS nights, when something so simple can be so complicated and tedious.  It happens all the time.  So for those of you who need a quick tutorial on download Vancouver Open Data, here is.

In this video, we’ll walk through how to download data from Vancouver Open Data.  If you’ve watched my other tutorials, you will notice that this is one of the datasets I do use. The last time I used this dataset was when I did a tutorial on label orientation and style (click here for a glance Part 1, Part 2, Part 3) and an awesome conversion to #KML to open in Google Earth.

As always, I do encourage using open data.  It’s free and accessible to the public.  One message to take home from this video is that orthophoto downloading are quite similar across all platform.  There is usually:

1) a metadata that will tell you about that data.  This is where you find out about the resolution, the features, what techniques were used to capture the data and how old it is.

2) You’ll usually be directed to a graphic screen comprised of tiles.  Some other resources like GeoBase, will actually let you direct download from their FTP.

3) When you do download, make sure you’re on a UTM project, especially if you are calculating area.

Happy GIS-ing