Showing posts with label Tutorials. Show all posts
Showing posts with label Tutorials. Show all posts

Saturday, March 17, 2012

Easy Method to Finding Coordinates

Here is a quick and easy way to find geographical coordinates when needed. Sometimes you may be given a task to find the location of specific coordinates (ie. -79.387014, 43.642768), or determine the specific coordinates to a certain location (ie. coordinates of Mt Everest).

Here are a few easy steps using my favorite, Google Maps (because it is free!) to find the coordinates (in decimal degrees) of a specific location.

1. Find a location you are interested in using Google Maps. I have chosen the Empire State Building.


2. Right click on your desired location and click "What's here?"


3. Check the Google search bar and your coordinates will be displayed. NOTE: The coordinates are displayed in opposite order. 40.748403, -73.985549 should be read -73.985549, 40.748403. This is read as -73.985549 west, 40.748403 north. Obviously if the latter is negative, then it is south, and the former is east when positive. It is read as longitude, latitude, but Google maps read as opposite.



Now if you would like to find where specific coordinates are, just place the coordinates in the search bar shown above. Remember, place North/South coordinate first, and then East/West.

Saturday, March 10, 2012

Calculating Distances Topographically in 5 Easy Steps

Have you ever wanted to calculated a distance birds eye view? That would mean finding the distance from one point to another in a straight line.

Here is a simple way to calculate distances using one of my favorites, Google Maps. I can use this tool for various objectives.

For example, last month I for some reason really wanted to know the distance it would take a boat to travel from one island to the next. Or swim of course. Here's what I did.

Here are 6 easy steps:

1. Sign on to Google via your personal Google account and then go to Google Maps. To satiate my curiosity, I decided to find out the approximate distance between the western most point in Alaska to Russia's Eastern most point. I wonder if you can swim the distance. 


Note: The feature I am about to show will not work if you do not have a Google/Gmail account. 





  As you can see from above, I have a Google Maps satellite view of Alaska and Russia.

2. On the pane to the left, you should see an option where it says "My Places". You will only see this if you are signed into a Google account. Click on "My Places"


3. Once you have done this, you will see a "Create Map" option in a lightly red colored box. Click this. It will give you an option to create a title and description for your map; you may skip this. What this essentially does is Google maps allows you to perform your own "light" GIS functions on Google maps. Such functions can be digitizing, drawing lines, creating points, etc...


4. Now, on the top left corner of the map, click on the "line" feature. This is the third option, next to the "point" feature which appears as a blue balloon. The point feature is between the line feature and the "pan" tool, which is the icon of a hand.

Ensure the "line" feature is actually on l"draw a line" feature.




5. Now that you are on the "draw a line" feature, you can calculate the distance between your two points of interest. Click on an original point of interest. The blue line will now begin. You may now drag this line to the next point of interest. In my case, I dragged it from the western tip of Alaska to the "Little Diomede Island". You will now notice the distance is automatically displayed as you drag the line. This is how you can find the distance quickly and efficiently between two points.




To my discovery, I see that Alaska and Russia are extremely close together, only about 86 kilometers apart. Hmm, I wonder how border security is? My my, the tension.


It is important to note some limitations. One large one to factor in is that you should not use this to calculate the distance between very far points of interests. This should be an obvious one as the Earth is round. Google Maps uses a projection system that would not account for this (UTM). No projection would actually account for this as there is always some sort of distortion in cartographic presentations of our Earth.

Well I hope this was an interesting free tool to learn. Good luck.

Tuesday, February 28, 2012

What is digitizing?

I thought it would be appropriate to add a few key terms in the GIS field. After all, I suspect many non-GIS users are now having to integrate some of their work with maps.

Digitizing in GIS is essentially digitally representing geographic features from a topographical perspective. Digitized records are in the form of a set of mathematical arrays, or more simply put, vectors.

When someone says "all the buildings in the Guelph cma have been digitized", they precisely mean than the outlines (depending on how detailed the user did it) of all the buildings in Guelph are now available in digital format.

Advantage: After digitizing, you know have a computerized record (spatially represented) of the object of interest. You can perform any types of modifications or analyses to this computerized record.


Above is an example of the Pentagon (because a pentagon shaped building is pretty cool) digitized. You can see to the left, I have the aerial image acquired directly from Google Maps. To the right, I used Google Maps once again, to create a polygon outlining the outer boundaries of the Pentagon, aka digitizing.

Coming soon: How to digitize with Google Maps, it is FREE!