The purpose of today’s lab is to gain an understanding of map and coordinate systems. We will be working with several layers today, and they might not have the best appearance at this stage of the course we will be addressing how to stylize layers as the semester continues. For today focus on how to locate data, what map scales mean, and how coordinate systems work.
Note that this lab includes 5 questions worth 5%. These are identified by number (1-5). Please make a title page with course number, lab section, and your name, and place answers to the questions you’ll find throughout this lab. Save the file as <username>_GEOG205_Lab2_<date>, and submit as an attachment with your email for Assignment 2
Canadian National Topographic System (NTS)
Canada’s national topographic map series (NTS) uses scales 1:1,000,000, 1:250,000, 1:50,000.
In this section, you will explore the map numbering conventions for the National Topographic System 1:50,000 and 1:250,000 maps and how their numbering convention is based on the 1:1,000,000 map series (as shown in lecture).
To understand the National Topographic System begin by imagining Canada divided into a grid 8 degrees of Longitude by 4 degrees of Latitude. The grid sheets are numbered bottom to top, and east to west.
Each NTS map sheet is a 8 x 4 degree region that is further divided into a 2 x 1 degree grid (examine the Graticule labels). Each 1:250,000 scale map sheet is given a letter of the alphabet from A to P. These letters are appended to the 8 x 4 degree grid number to create the 1:250,000 scale map sheet number. Prince George is located on 093G. Note how the letter designations start lower-right corner and wind back and forth up the grid, ending upper-right.
Each NTS 1:250,000 sheet is further subdivided into a ½ degree x ¼ degree grid (30 minutes Longitude x 15 minutes Latitude). These 1:50,000 map sheets are numbered 1 to 16 and these numbers are appended to the 1:250,000 map sheet number. Prince George is on map sheet 093G15.
You have just seen Canada’s National Topographic System (NTS) for south of 68N. The1:250,000 NTS grid is 2 x 1 degrees and the1:50,000 NTS grid is 30’ x 15’
This far north note how narrow the widths of the map sheets have become compared to the lengths (height). The northern parallel of latitude of sheet 56 is 68 North.
The northern parallel of grid sheet 59 is 80 North Latitude. North of 80, the width of the 1:250,000 map sheets doubles, to 2 degrees of Longitude. The primary grid (1:1,000,000) also doubles in width creating a 16 Longitude x 4 degree Latitude grid.
Full national index is at http://www.maptown.com/topographicalmaps.html
click on areas of interest to zoom in (more than once) on map sheet numbers
Or this interactive map: NTS Map (arc.gis.unbc.ca)
Detailed information on the topographic series at:
NTS Map sheets for BC
Now, you will examine Canada’s NTS map sheets for BC in ArcGIS Pro
- Create a new project in ArcGIS Pro for Lab2 inside your GEOG205 folder on the K drive.
- Open My organization’s content in the Portal Catalog, and add the following layers BC Rivers, BC Lakes, BC Highways, Populated Places, BC Cities, and BC Boundary.
To draw the grid over the map we first need to add some more data to our project, in the Catalog, move over to the Project tab, and right-click on Folders and add new add L:\DATA
Now you should be able to expand into the nts_snrc folder and add the shapefiles for nts_snrc_1m, nts_snrc_250k and nts_snrc_50k.
In the table of contents arrange the layers such that 1:1 000 000 is the top layer followed by 1:250 000 and 1:50 000.
Disable nts_snrc_1m, and nts_snrc_250k, by pressing the check mark. Then select nts_snrc_50k.
Double-clicking on the colour below the layer name will open the Symbology panel -> select Black Outline. (Note: You can change the colour of the 250k and 1m layers to outlines as well to prevent them from covering the other tile layers, we will talk about symbology more in a future lab).
On the top menu select labelling. Turn on labels by clicking the tag on the far left, and set Field to NTS_SNRC.
Now to make the labels readable, set the font to a Sans-Serif (ie Arial), Size 16pt, and then in the extended type options (the arrow to the lower right of the pane)
You can add a Halo
And finally in the label placement block, select “Land Parcel” so that the labels always show inside of their region.
We can now use this map to locate the tiles we will be using.
In a future lab we will be doing a deeper look into the advanced symbology / labeling tools that will allow us to combine all three of these layers, much like the interactive map seen above.
British Columbia TRIM
BC provincial data are produced at a 1:20,000 scale. The map sheets for TRIM (Terrain Resource Information Management) are also based on the 1:250,000 map grid. Each sheet of the entire 2 x 1 degree grid that covers British Columbia is divided into 12 minutes of Longitude x 6 minutes of Latitude grid. This creates 100 TRIM map sheets per 1:250,000 map sheet.
The TRIM sheets are numbered from 1 to 100. These numbers are appended to the 1:250,000 sheet name. British Columbia is covered by 7,027 1:20,000 TRIM map sheets.
In ArcGIS Pro, add the layer “BC 20k Grid”, from the portal.
Examine the 1:20,000 map name system and explore the map.
Toggle BC 20k Grid on and off to see the division of each 1:250,000 map sheet into 100 TRIM sheets.
What is the number of the TRIM map sheet immediately above 093G.025?
Other Provincial Topographic Data Sets: Alberta Map Names
The map sheet grid for Alberta provincial topographic digital data is also at 1:20,000 scale and is based on the 1:50,000 30′ by 15′ map sheet grid. Each 1:50,000 map sheet is divided into Northeast, Northwest, Southeast and Southwest quadrants. For example, if you wanted a 1:20,000 map sheet covering most of downtown Calgary; you would go to NTS tile 82O then select the Alberta tile 01SE.
Map Name Conventions and Scale – Don’t Let the Name Fool You:
At what scale would the data for grid map 093G7 be produced ? As 093G7 does not follow any of the naming conventions we have seen thus far (NTS or BC TRIM), there is no way of knowing what data set or scale of data is referenced. If the naming conventions were correctly written, then 093G07 is 1:50,000 NTS and 093G007 is BC TRIM 1:20,000 data. Note the two digits for the sixteen 1:50,000 sheets, and the three digits for the 100 TRIM sheets. TRIM map sheet numbers are also written as 093G.007 using a period before the sheet number.
To add to the mix: You may still find 1:50,000 scale paper maps from the NTS system in east and west sheets. For example, 093G16E and 093G16W were printed at a time when they split the 1:50,000 sheets into E and W halves. This map sheet was possibly never updated.
Comparison of image with 1:50,000 map vectors
Next, add the image “Prince George 2002 Ikonos” from the portal.
Right-click ikonos_02 and select Zoom to Layer
Examine the image. Note the detail. A display scale between 1:10,000 and 1:30,000 is appropriate for this step. Pan around the image and note the detail of the area (4 metre pixels). This (satellite) image was captured in 2002.
Turn on layers one at a time to note the simplification of the vector layers compared to the features on the image.
- Add rivers_093G as the 1:50:000 vectors
Examine the level of simplification between BC Rivers, and rivers_093G.
Paper Map Digital Scans
Add Data NTS_093G_tif from the portal
Turn off all the other layers so only the new map is visible. At this point you will notice that the map is stretched out, this is due to being in a different projection from our map view. We will talk more about projections later in the course, but for now double click map at the top of the table of the drawing order
Then go to Coordinate Systems, and look for the available Coordinate Systems. Expand the following folders until getting the projection NAD 1983 UTM Zone 10N: Projected Coordinate System / UTM / NAD 1983 / NAD 1983 UTM Zone 10N
Select it, press OK, this will set our map view to the proper projection.
You are examining a digital scan of the paper map.
Zoom In and Pan around. Note the coordinate readout changes as you move the mouse. A digital scan of a paper map can be georeferenced (this is not always true).
Note the markings at the edge of this 1:250,000 map sheet. The Graticule around the map is labelled with Longitude and Latitude values, illustrated with black and white bars (circled in the illustration at left). At this scale, these bars represent 5 minutes.
Note the pale blue grid lines at four centimetre intervals across the paper map. This is the measured grid. At a scale of 1:250,000 four centimetres represents 10,000 metres (10 km) in the real world. Near the four map corners of the map are label values. In the example below, the intersection of the blue lines is marked by the red dot. The x,y coordinate for this dot is: 560000, 5980000 as shown by the blue labels. These values are in metres. X values, known as Eastings, increase from left to right (increase in the easterly direction).Y values, known as Northings, increase from the bottom to the top of the map (increase in a northerly direction).
The notes above also apply to other scales of paper maps, except that the Graticule and measured grid intervals would change with scale. For example the Graticule interval for 1:50,000 NTS paper map sheets is one minute, and the UTM grid interval is 1,000 metres.
The paper distance across a blue measured grid square is 2 cm. On a 1:50,000 scale map, 500 metres is represented by one cm, or half the width of the blue measured grid square. One hundred metres are represented by 2 mm on a ruler.
Reading UTM values from printed maps
The South tip of Tabor Lake (east portion of map) has these UTM Coordinates: 529350E, 5972750N, 10N
Longitude / Latitude (LL) : 122 degrees 33′ 12″ W, 53 degrees 54′ 8″ N
To get a more up to date and detailed map of Prince George go into the Portal in the Catalog pane and add 093G087_tif
What are the UTM and LL values for the junction of the entrance road into UNBC from University Way?
[ give LL in ‘DMS’ format]
What are the same values for the control tower at PG airport?
Digital Coordinate Readout
Zoom In on a corner of the map so that you can see the coordinates, and notice that the coordinate readings for the map cursor match these labels.
There is a 2nd set of coordinates in blue these are UTM labels. By pressing the arrow beside the coordinate readout we can change into UTM.
- Hold your mouse over the intersection of the blue measured grid lines. The digital coordinate read-out should match these values.
You can turn the whole image on and off. There are no individual layers (e.g. you cannot turn off roads in this raster scan of a paper map).
If you query this scanned map datasets, a single pixel flashes listing the colour values. No map attributes are attached. You cannot change the symbols. Use the Identify tool to click on the raster – note the cell values. In ArcGIS Pro the Identify tools are found in the Map Ribbon and Active when “Explore” is selected, you will also notice a drop down that alters the behavior of what is identified. The default is Topmost which will show information for whatever is the highest layer i the drawing order. Another common option is Selected on Contents allowing you to highlight a layer to get information even if it is obstructed by an above layer.
UTM Zones for BC
Note that in UTM the coordinates come in 3 parts: X, Y, and Zone. X and Y are in metres and represent a distance from a point, but what is that point? Well it depends what zone you are in. UTM divides the earth in 60 slices each 6 degrees wide, and then is cut through the equator to divide these slices into North and South. As an example BC falls within the 10th ‘slice’, and is in the Northern Hemisphere, giving UTM Zone 10N.
There is an interactive map available here that you can use to explore where these Zones exist https://mangomap.com/robertyoung/maps/69585/what-utm-zone-am-i-in-#
Just south of Prince George you will find Beaverley and Buckhorn.
On the map tab you will find the measure tool.
With this tool selected you can click on two points and get the distance between them. By default the tool will measure Planar distance, this is perfect for today’s uses, as we start to work with larger areas you may want to start using geodesic measurements to account for the shape of the earth.
What is the distance between Beaverley and Buckhorn?
You can also measure areas, by clicking the arrow below measure and choosing Measure Area, you can now make a series of points, double clicking to finish the selection and ArcGIS Pro will calculate the area surrounded by the area you make. Zoom into Ten Mile Lake near the South East corner of the map. And roughly measure the area of the lake.
What is the area of Ten Mile Lake in hectares?
Determining Map Sheet Names and Numbers
There is a Provincial park northwest of Prince George called Eskers. Using the BC 20K Grid layer you added in ArcGIS Pro, identify the TRIM tiles corresponding to the features below.
How many 1:20,000 map sheets are needed to cover the Eskers provincial park?
Which 1:20,000 map sheet (using the NTS naming convention for BC TRIM sheets) includes most of the city of Quesnel (south of PG by ~111km)
PG Map is a website using ESRI Geocortex, an application very similar to the portal for ArcGIS Pro we are using in this class (https://arc.gis.unbc.ca/portal) but with a bigger emphasis on publishing data to the public as opposed to within your oganization.
You can access PG Map here:
In the map you will find many familiar tools such as the table of contents on the side showing all the publicly available geospatial data from the City.
Spend a few minutes exploring the map, look at different layers and explore what the tools in the tool bar do.
Now we will look specifically at the Coordinate widget
You will find it along the bottom of the map
You will see that you have various options for the format of the coordinates
At this point we are familiar with a couple of these, UTM, and 4326 DMS, DMS stands for Degrees Minutes Seconds. The default in this list is Lat/Long where coordinates are expressed in DD or Decimal Degrees, and we also See DDM, Degrees with Decimal Minutes.
As to why you would pick each of these is a matter of what you are trying to comunicate, for making maps you should always try to avoid 4326 as this is the code for unprojected data, however DMS is still a great format for sharing point data especially for people navigating with a compass. UTM is helpful as coordinates match to real world distances, but has limited uses as maps begin to cover very large geographic areas, but at city scale this is a great choice.
You may have also noticed WKID: 102100 X/Y in the list, you should avoid sharing coordinates from this system to maintain conventions. However this is probably the projection you are the most familiar with, as this is the same projection used by Google/Bing/Apple Maps, however these apps generally always convert to DMS or DD before providing coordinates to end users.
Using PG Map – What is the UTM Coordinates of the GIS Lab at UNBC (see photo above for location once you are on campus)
What are the DMS Coordinates of City Hall in Prince George?
What are the DD Coordinates of the Band-Shell in Lheidli T’enneh Memorial Park?
give your answers without decimals of metres or seconds.
-it is illogical to be so precise for features which are tens of metres in size
Send to your TA before start of lab next week.
Extra: BC provincial iMap website map viewer: https://maps.gov.bc.ca/ess/hm/imap4m/
You will see some similarity to PGmap in how the BC map viewer is organized. The format is a bit annoying in half the screen lost to menu options. Try the coordinate widgets and you’ll see the addition of the BC Albers system. Click on “I want to …” and ‘add provincial layers’ to see the range of BC data layers are at your disposal. The imagery -> DataBC Orthophoto displays photomosaics for the whole province and DataBC Imagery, satellite imagery and elevation.