The purpose of this tutorial is to familiarize you with the maps feature of the SAS Graphics Accelerator. The outcomes of this tutorial are as follows:
Having a basic understanding of map concepts is critical to this tutorial. In this section we cover the global coordinate system, the imperial distance system, and three direction systems. Even if you are familiar with maps, we recommend that you read through this section as a review.
When examining a map, it is helpful to imagine yourself standing at a location looking at the things around you. This is called your virtual location, since it may not be where you are actually located in the real world. To identify a virtual location, you must understand the system used to locate things on Earth.
If you imagine the globe, you can draw imaginary lines around it; some of them go left and right, while some go up and down. The ones that go left and right are latitude lines and always run parallel to the equator. These measure how far north or south a point is, and run from 0 degrees at the equator to 90 degrees at the north and south poles. The imaginary lines that go up and down are longitude lines and always pass through both the north and south poles. They are used to measure how far east or west a point is, and run from 0 degrees near England through positive and negative 180 degrees on the opposite side of the earth. Positive numbers measure how far east a point lies, while negative numbers measure how far west a point lies. You can use latitude and longitude to uniquely identify any point on the Earth's surface.
Distance is how far two points lie from each other; this is always the most direct route between the two points. In the SAS Graphics Accelerator, distances are measured in miles and yards. There are 1,760 yards in a mile. One yard is equal to three feet.
Directions are the most tricky, since there are several systems each trading accuracy for simplicity. In the SAS Graphics Accelerator, you can switch between three direction systems.
The most familiar to many people is the cardinal direction system; this system will be familiar to you if you have ever used a compass. If you are standing on the globe facing the north pole, north will be directly ahead of you, east will be to your right, south will be behind you, and west will be to your left. As you spin around in-place, the directions will not move with you. North always is the direction to the north pole, south is always the direction towards the south pole, etc. If you need more than four directions, you can combine north, east, south, and west to create a total of eight directions. For example, northeast is half-way between north and east. If you want even more directions, you can combine those eight directions to make 16 directions. For example, north by northeast is half way between north and northeast. If you were to point directly north, and spin around in a circle to your right, you would encounter the 16 directions in the following order: north, north by northeast, northeast, east by northeast, east, east by southeast, southeast, south by southeast, south, south by southwest, southwest, west by southwest, west, west by northwest, northwest, north by northwest, and finally back to north. This means that if a point lies in a direction with north anywhere in the name, it is somewhere in front of you, and if south is anywhere in the name, it lies somewhere behind you.
Another direction system that you may be familiar with is the face of the clock. This system has 12 unique directions, with 12 o'clock directly in front of you, 3 o'clock directly to your right, 6 o'clock directly behind you, and 9 o'clock to your left. If you were to point directly at 12 o'clock and spin to your right, or clockwise, you would point at 1 o'clock, 2 o'clock, 3 o'clock, etc. until you get back to 12 o'clock again. The clock face direction system is different from the cardinal direction system since it moves with you as you spin in-place. In the SAS Graphics Accelerator, you are always facing north though, so you can think of 12 o'clock always corresponding to north, 3 o'clock corresponding to east, 6 o'clock corresponding to south, and 9 o'clock corresponding to west. This means that all of the directions between 9 o'clock and 3 o'clock, passing through 12 o'clock are in front of you, while all of the directions that lie between 3 o'clock and 9 o'clock, passing through 6 o'clock are behind you.
The bearing direction system may be the least familiar to most people, even though it is the most accurate. It gives the directions as degrees around a circle, with 0 degrees being directly north, 90 degrees being directly east, 180 degrees being directly south, and 270 degrees being directly west. If you were to point at 0 degrees and spin to the right in-place, you would pass through 0 degrees, 1 degrees, 2 degrees, etc. all the way through 359 degrees before pointing at 0 degrees again. This means that any direction that is greater than 90 degrees and less than 270 degrees is behind you, while any direction greater than 270 degrees and less than 90 degrees is in front of you.
Combining all of these systems, you can think of exploring a map like walking around in the real world. You have a virtual location, which is where you are located in this map. You always face north, and hear where things are around you. You can think of this like touching things with a virtual cane; you can touch points in front of you, to your left and right, and behind you, but you don't have to change the direction that you are facing to do so. As you change your virtual location, you will be able to reach different points with your virtual cane. We will use this metaphor as we learn how to use the SAS Graphics Accelerator.
In this section, we discuss how to install and launch a map within the SAS Graphics Accelerator. If you are already familiar with the SAS Graphics Accelerator, you only need to know that you launch a map in the same way as any other graph, such as a bar chart or heatmap.
The SAS Graphics Accelerator is a freely available extension for Google Chrome that allows nonvisual exploration of various charts and maps. To install it, you must be using Google Chrome on either a Windows computer or a Mac.
Navigate to the SAS Graphics Accelerator's Google Chrome page and follow the instructions to install it. Once you do that, you may have to restart Google Chrome before refreshing this tutorial. To check if it is installed correctly, you can look for buttons on this page that say "Accelerate X", where X is the name of an example map.
To launch a map, you will see a button called "Accelerate X", for example "Accelerate Example 1". Pressing this button will launch the SAS Graphics Accelerator in a new tab with the map already loaded. After exploring that map, you can either close that tab or switch tabs back to the tutorial. The next time you activate an accelerate button, the SAS Graphics Accelerator will automatically detect that it is already running in in a background tab and reuse that to display the new map.
When the SAS Graphics Accelerator launches, keyboard focus will be placed on the map itself. There are other controls on the page, but none of them are relevant for this tutorial.
There are two ways to control the SAS Graphics Accelerator when working with map data. One way is by using a standard keyboard. Throughout this tutorial, we will give the keystrokes to perform an action. The second and more powerful way is by using a gamepad, also known as a video game controller. We recommend using a gamepad since it has useful controls that a standard keyboard does not. The most important control is the thumbstick, which allows you to quickly scan in all directions using the virtual cane. If you want to tuch objects to your right, you simply move the thumbstick to the right. If you want to explore what's in front of you, you push the thumbstick forward. Moving the thumbstick to control the virtual cane will allow you to build your understanding of the map faster than by simply pushing buttons on a keyboard. Note that not all actions are available on a gamepad, you may still have to use a keyboard to adjust some settings.
This section presents a quick overview of a gamepad in case you are not familiar with the layout. We recommend Microsoft branded gamepads since they tend to have a more standardized layout and are easier to get working with Mac and Windows computers. Both Microsoft brand Xbox 360 and Xbox One gamepads have been tested with the SAS Graphics Accelerator.
For this overview of a gamepad, ensure that it is orientated so that the gamepad's grips are towards your body and the buttons are facing up.
The controls in this section are all found on the top of the gamepad.
The controls in this section are found on the back of the gamepad, facing away from your body.
In this section you will learn how to explore a map within the SAS Graphics Accelerator.
The SAS Graphics Accelerator presents maps in a first-person perspective. This means that you can think of a map like actually standing at a location in real life. You can see the points around you and move closer and farther away from what you are examining.
When exploring the points around your virtual location in the SAS Graphics Accelerator, you will hear the name of the point, the point's distance from you, and the direction of the point. For example, you may hear the text "Library, 2 miles at 12 o'clock". You can break down this sentence as follows:
On a keyboard, You can use the "C" key to toggle through speech verbosity settings. Below is a discription of each verbosity mode:
One thing to remember is that touching a point with your virtual cane does not change the direction that you are facing. In the SAS Graphics Accelerator's maps, you always face north. You can think of it like pointing a cane at something in the real world; you can point your cane to the left, right, or even behind you, but you don't necessarily have to change the direction that you are facing to do so.
In the below map, Example 1, you can explore three points. The point called "Moe's Tavern" is to your 8 o'clock, the point "Nuclear Power Plant" is to your 12 o'clock, and the point called "Barney's Bowl-A-Rama" is to your 4 o'clock. On a gamepad, you can sweep your virtual cane around you using the right thumbstick. Move it in a direction to hear if a point lies in that direction. If there aren't any points, you will not hear anything. If you do find a point, you will hear a sound and then hear the direction and distance of that point as previously described. If you are using a keyboard, you can press "page down" to touch the next point with your virtual cane moving in a clockwise direction, while pressing "page up" will touch the next point with your virtual cane moving in a counter-clockwise direction. Your virtual cane will always touch the next point, so you don't have to worry about finding empty space.
By default, the SAS Graphics Accelerator also plays a sound to represent the location and distance of the point when you are touching it with your virtual cane. If the point is located to your left, the sound will come from your left speaker; if the point is to your right, the sound will come from the right speaker; and if the point is in front or behind you, it will come from both speakers. Points near your virtual location have a higher pitch, while points farther away have a lower pitch. For now, you can disable the sound so you can focus on the speech by pressing the "S" key on a keyboard until you hear "off."
Note that if you are using Jaws or NVDA, you can disable command echo with jaws/NVDA key + 2. This will prevent your screen reader from speaking unnecessary information.
When you want to find a point's direction with more accuracy, you can change the direction mode. Below are descriptions of the three direction modes that the SAS Graphics Accelerator supports.
The next map, Example 2, contains additional points. Practice switching the direction mode with the "I" key on a keyboard to see how the modes are related to each other. Remember that you can turn off the sounds with the "S" key.
When exploring the points around you, you are only able to see the points within a certain distance of your virtual location. This distance can be set very large to show points that are far away from one another, or very small to see only nearby points. You can control this distance by setting the zoom level; zooming in will show a smaller region of the map, while zooming out will show a larger region. Note that zooming does not change the distance between points, it only changes how much of the map that you can see at one time. The largest zoom level will show you half of the Earth at one time.
When you first launch a map in the SAS Graphics Accelerator, the software will attempt to show you all of the points. You can use the "=" and "-" keys on a keyboard to zoom in and out respectively. On a gamepad, you can zoom in with the top face-button and zoom out with the left face-button. As you change your zoom level, you will hear the maximum possible distance that you can see at that zoom level.
You can think of this like changing the length of your virtual cane. As you zoom in, your virtual cane gets smaller and you can only touch closer things. Zooming out makes your virtual cane longer, and you can touch things that are farther away. The maximum that your virtual cane can reach is a quarter of the globe to the west and a quarter of the globe to the east. This means that you can see half the globe at once when zoomed out as much as possible.
Use the below button to relaunch the map called Example 2. First, try to count the number of points that lie within 1,000 yards of your location without changing the zoom level. Then, zoom in using the "=" key on the keyboard or the top face-button on the gamepad until you reach the 1,000 yard zoom level, and then count the points again. Notice that it is much easier to count the points when zoomed in since all of the other points are no longer visible.
You can move your virtual location in three ways. Using the arrow keys on the keyboard and the d-pad on the gamepad, you will slide your virtual location in the direction of the arrow at a distance that is one-fifth of your zoom level. For example, if your zoom level is ten miles and you press the right arrow or right d-pad, you will move your virtual location two miles to the right. The speech will also tell you how many points are in view of your new virtual location at your current zoom level as well as the total number of points on the map. For example, you may hear the announcement "1 mile left, showing 11 of 16 objects". This can be broken down as follows:
As you move your virtual location to the left or right, you will stay on the same latitude line. This means that you will always maintain your same distance from the equator. The same thing applies when moving your virtual location up and down; you will stay on the same longitude line.
Since the globe is a sphere, moving your virtual location to the east will eventually wrap around and you will approach your starting location from the west. The same thing will happen if you move west, but you will eventually find your starting location but approaching it to the east. The SAS Graphics Accelerator prevents you from crossing the north or south pole, so you will hear a "top of map" error message if you try to go too far north and a "bottom of map" error message if you try to go too far south.
Another way you can move your virtual location is to jump directly to the point that you are touching with your virtual cane using the enter key on the keyboard and the right trigger on the gamepad. This will automatically move your virtual location precisely on top of the point, meaning that it is easy to get the exact distance and direction to other points just by touching them with your virtual cane.
The final way to move your virtual location is using the jump dialog. This dialog allows you to search for the label of any point on the map and move your location directly to it. If there are more than 200 points on the map, you will have to use the dialog's search box to type part of the label, and then choose your desired point from the list. To activate the jump dialog, press the "J" key on the keyboard.
Practice moving around the map below. For more precise movement, zoom in, move in the direction that you want to, and then zoom back out to your previous zoom level. If you get lost, you can press the "0" key on the keyboard to return to the starting location and zoom level.
As you may have noticed, the SAS Graphics Accelerator also uses sound in addition to speech to indicate both the direction and distance of a point. Depending on the direction of the point, the sound that plays when you focus on it will appear to come from that direction. For example, if a point is at 9 o'clock, the sound will play primarily out of the left speaker; 3 o'clock will play primarily out of the right speaker; and a point in front of you will play out of both speakers equally. To tell the difference between a point directly in front of you and a point directly behind you, the SAS Graphics Accelerator plays points behind you with a more metallic or electronic sound.
The pitch of a point is linked to how far it is from your virtual location relative to the current zoom level. As the point is closer to you, its pitch is higher; as the point approaches the maximum distance of the current zoom level, its pitch decreases. This means that all the following examples would result in the same pitch being played:
the SAS Graphics Accelerator will play the sound associated with the point that you are touching with your virtual cane. Any time you move your virtual location or change the zoom level while touching a point with your virtual cane, the SAS Graphics Accelerator will replay that tone in the new location. This allows you to track the point as your perspective changes. If you can no longer reach the point with your virtual cane, you will not hear any sound at all. You can also replay the sound with the "space" key on the keyboard.
Reopen Example 3 below and listen to how the pitch and direction of the sound changes, especially when you move. When listening to sonification, we recommend headphones for an optimal experience.
The SAS Graphics Accelerator has a built-in help page, accessible by pressing "H" when navigating a map. Below is a quick recap of the most important keyboard and gamepad commands: