“Lesson 3d: Using the draw tool in The National Map Viewer”
“The National Map viewer is a primary access point for the ‘visualization’ of geospatial
data that composes The National Map and functions as a tool to enable use of the data in a web
environment.
This is the second of three short lessons that provide the user with an overview and
demonstration of some of the more advanced functions of The National Map viewer including
how to add data, draw on, and select data.”
“By the end of this lesson, you will be able to use the draw tool to add data to the
map and measure distances in the National Map Viewer.
The next lesson demonstrates how to select data from the map, and take actions on it.“
“The National Map viewer serves as a window into freely available base map data that is
consistent on a national level, and provides resources to access the data through a variety
of products and services.
To access the viewer, launch a web browser and navigate to the link shown.”
“For help at any time, click the “Help” hyperlink located in the footer at the lower
right.
This is a temporary location for the link due to system error.
The original location of the “Link to Help” hyperlink is shown here in the upper left.”
“The draw tool button is located at the top right of the viewer and looks like an
artist's palette with paint brush.
Click on it to enter drawing mode.
This opens the draw window that offers a number of drawing modes from points to lines and
various polygons.
A text option is also available” “Lets select the point option.
Once a drawing mode is selected, additional controls will appear in the window.
For points, options include choosing a set of symbols, and selecting a symbol size, color,
transparency, outline color, and outline width.
The actual number of options varies depending on which symbol is selected.
Many have only the size option.
To see the available symbol sets, click on the down arrow below the symbol preview.
A list of the symbol sets will open with the current set in bold.”
Click on the set you wish to use.
When you click on a specific symbol, only the available options for that symbol will
be displayed.
When the campsite symbol is selected, all options but size disappear.
Also note that there are more symbols available in each set than fit in the display window.
A slider bar allows you to scrolling through the entire set.
Change the size of the symbol with the up and down arrows to the right of the symbol
size.
Notice that the symbol preview changes to the size selected.
To place a symbol on the map, simply click at the desired location for placement.”
“You can also add your own symbols to the map.
Scroll to the bottom of the list of symbol sets and click on custom image.
For best results, your symbol should be 16 x 16 pixels, but other sizes will be automatically
adjusted.
Supported image formats include PNG, GIF, and JPEG.”
“The measurement tool demonstrated in lesson 3B measures distances on the map only in straight
lines.
You can use the draw tool to do more precise measurements on nonlinear features.
This comes in handy when you want to measure distances along roads or trails in mountainous
areas.
Select the freehand polyline from the drawing modes.
At the bottom of the options check the ”show measurements” box and use the associated
drop down menu to select the units of measure.
Trace the feature to be measured by holding down the left mouse button and tracing.
Release the mouse button to stop tracing and see the result.
Areas and perimeters can be measured using other drawing modes.”
“Let’s add some text to the map.
Click on the draw mode button labeled with a capital A. Type the text you wish to entered
into the text box below the draw mode buttons.
You can also change the font size and text color using the control boxes below the text
box.
Click on the map where you wish to add the text and it will appear.
To remove your drawing and text from the map, click “Clear”.”
In this lesson, we discussed how to add data by using the draw tool in The National Map
viewer.
Additional lessons will demonstrate other advanced tools available within The National
Map viewer.