Digitizing will take two weeks.
 

Assignment WEEK ONE: You will use the editing tools in ArcMap and Maptitude to create and edit points, lines, and areas.  Screen Capture will show that you know the basic editing tools. Assignment WEEK TWO: You will use a digitizing board to create a new coverage of the lower 48 United States.   You will add points, lines, and areas to this map using the digitizing tablet.  If possible, choose a map which will be useful for the indexing project.  It may become a permanent resource for that assignment. Read ahead and see the layers that already exist for that assigment here.

The first task is to become familiar with the "heads-up" digitizing in both Maptitude and in ArcGIS.  You'll see the way these two programs allow editing of spatial layers.  To prepare the smart classroom for the digitizing assignment, make a subdirectory in C:\temp called 391.  Copy the entire subdirectory p:\g&es391\digitize and put it in C:\temp\391\ .

• Add a few points
• Delete some points.
• Move some points.

• Add a few lines (double-click to end)
• delete a line
• reshape a line
• split a line, then delete part
• digitize crossing lines, join the segments with the merge tool, then select the endnodes of each crossing line and then click on the intersection to put an endnode there. You can then move the intersection and all segments will reflect that move.

• Add a few isolated polygon areas
• delete an area
• add an adjacent area
• adjust the boundary of an area
• join two isolated polygon areas
• digitize an interior area in another polygon
• merge two adjacent areas
• add an interior border to split an area

 

 
 
 

Note about various polygon types

• Simple polygons are merely closed with a double-click
• Adjacent polygons snap to vertices or to edges
• Fragmented polygons are created when non-adjacent polygons are joined
• Any polygon may be split with the addition of a new crossing arc
• when editing a polygon, double clicking will add a vertex


Note about Attributes
When joining or splitting polygons you must be aware of the underlying attributes.

• blank -- delete the data from this column
• copy -- copy from the FIRST SELECTED polygon to the other
• add -- sum data for the new polygon
• divide -- reapportion the data according to area, when splitting
• highest -- take the highest value of the two
• lowest -- take the lowest average of the two
• average -- average the two

ARC MAP HEADS UP EDITING

In ArcMAP you'll have most of these and many other editing tools.  Start a new map and add your layers.  You would make new layers with Arc Catalog (File, New, Shape file). Start the editing tools with the Editor Toolbar on the top menu.

• Editor, Start Editing -- you are now in "Editing" mode and a variety of options come available
"snapping" lets you snap to vertice, edge, and/or end node
"options" lets you set the snap tolerance and stream tolerance (rt-click on map to activate)
• the "edit" tool lets you see, and move, insert and delete individual vertices.  double-click to select object
• the drawing tools let you draw straight/curved edges or drop points
• there are some special tools here too --  These are useful when digitizing a description, such as "the property corner boundary is 100 feet from the corner of the building and 76 feet from the fire hydrant."  If you draw two circles of 100 ' and 75 ' radius; their intersection is the corner of the property boundary. Intersection is similar, but it draws tangent lines to existing polygons.
• The Task Bar determines what it is you're doing with the tools (I've boldfaced the most important ones):
• Create new feature -- just as it sounds
• Auto complete polygon -- uses existing chain as one edge of a new polygon.  Just overlap an existing polygon.
• draw a line across a polygon to split it into two
• Select features using a line/area -- just as it sounds (but remember, the Selection Setting determines whether intersecting objects are selected)
• Extend/Trim features either lengthens a line or cuts it to a newly drawn reference line.
• Mirror feature -- creates a mirror image across a drawn line
• Modify feature -- lets you move an object or individual nodes
• Reshape feature -- like autocomplete, but makes one polygon (adds or removes from polygon)
• Cut Polygon Features -- cut one polygon into several with the line tools
• Current Target Area -- lets you set which layer is being edited
• Rotate -- lets you rotate a feature on the map
• Split -- lets you cut a line segment
• Shared edit -- lets you move an intersection or shared border
• Attributes -- lets you see (and when editing, edit) attribute values

The Editing menu also allows these operations

• Merge, combines two polygons or lines into one object
• Clip lets you clip out a portion of one polygon with another, for example, to reduce the extent of a map.
• Union, like merge, but creates a new polygon
• Intersection, creates a new polygon that is the intersection of those selected
• Move -- precisely by coordinate

In Maptitude

TASK	CHECK OFF
Points -- add points, delete some and move some
Lines: Draw a line and break it
Lines: Draw lines that are connected at an intersection.  Move the intersection to show that they are a network.
Area: simple isolated polygon
Area: reshape a polygon
Area: split a polygon
Area: adjacent polygons
Area: join or merge adjacent  polygons
Area: perforated polygon
Area: make a fragmented polygon
Show that you can use these tools with a "before" and "after" screen capture.  The area layer should have some fictitious data typed into a field, and this field displayed with the automatic labels icon on the top toolbar.  That way, when you join, split, or perforate, the data will reflecte these changes.  Consider changing background color by right-clicking the map canvas.

HINT: To show your work you may want to use the Selection Toolbar.  Ask for a demonstration in class.  Basically, this toolbar will let you name selection sets, and assign them different properties (color, pattern, etc.)  There is an icon on the selection bar that will display selected only, or all objects.

also you must use these editing tools in ArcMap
ArcMAP

TASK: AREA LAYER ONLY	CHECK OFF
simple isolated area
reshape area
split area
create an adjacent area
join or merge an  adjacent area
perforated area
take "bite" out of area with reshape
use the intersection tool to digitize a polygon, referring to other polygons (see demonstration).

Hint: ArcMap makes it very easy to copy polygons and move them.  You might want to do this step-by-step, always working on a copy, to leave a clear progression that shows your work.  Or, use a before-after shot as you did with Maptitude.

Annotate it thoroughly! Here's an excellent example of this assignment, with exemplary annotation.

You will use the basic editing tools with the tablet, the summasketch board, which is about a foot and a half square - only the center 12 inches is live. There should be 5 summasketch IIIs in the lab.

DIGITIZING IN MAPTITUDE
Preparing your map
Please find a map to digitize, and note the projection, if it is given.  You may find this base map (linked), with a Mercator projection, to be helpful.

Digitizing with the tablet
Before digitizing, we want to ensure that the features will be located correctly.  To do this we must "register" the map.  If you adjust the location later, the correct term is "rectification."  There are several common ways to register a map.

1. link points on the paper map with latitude/longitude coordinates.
2. link points on the paper map with points on an existing digital layer
3. link points on the paper map with points saved in a registration file

Start Maptitude

The first step is to bring up the state boundary file, which is in shape file format.  File, Open, SHAPE FILE, and look in P:\G&ES91\391USA\SHAPE for a file called "state."  When you open it, you will also be prompted to save the Maptitude-version of the layer (a .dbf file) to your folder on the C:\temp\ drive (you can make a folder there if you need to, just before you save you layer).

Next you will make a new geographic file (point, line, or area).  Remember to add in any attribute fields you may need to add useful data for your layer.  For example, for rainfall, I might add a character field called "range" in which I'll put "0 - 10," an integer field called Minimum, another called Maximum, and a real number with one decimal called Average.  Into these I'd put 0, 10 and 5, respectively for the "0 - 10" polygon.  This will allow searching and queries any number of ways.  Give the layer AND the shape file a descriptive name; in my case "rainfall."

USING THE DIGITIZING BOARD

• You must turn on board before you turn on the computer; reboot if the board is not already on. The switch in the back left, and the light will come on.

FIRST TIME SETUP
• If there is another map on the board, remove it. On your paper map, mark x's around the outer boundary and number them 1 to 15 or so.  Add a few that are interior.  They should all be identifiable on many U.S. maps.  If your map shows states in addition to country boundary, use state corners for your internal registration points -- these are commonly shown.  Use large coastal features around the edges. Slide your paper map securely under the plastic flap.

Next, you will register your map.
• Tools, Digitizer Setup

You will be asked for a projection.  If you're using the one I prepared, your map is a U.S./Canada Mercator projection.
Change the projection of the on-screen map to Mercator as well (File, Properties, Projection).
• Click on Maptitude's leftmost button (add control points).

The mouse will cease to function properly, but the puck will take over.  As you move the puck over the paper map, you should see the coordinates changing at the bottom of the screen.
• Register your pencil marks on the paper map sequentially then press the keyboard ESC

You should see as many rows of 00s as points you have registered. Make sure the top row is highlighted, and
• Click on Maptitude's fourth button (the little world map, true location)
• With the mouse, click on the corresponding places on the map on the screen -- DO NOT HIT "REGISTER" YET
• (Another way to do this would be to type in the latitude and longitude coordinates which you can find by using the arrow tool in Maptitude and drift over the corresponding points on the U.S. map).
• Save the computer-side digitizing registration to a file (this can be retrieved by Loading)
• Click on REGISTER

It should say registration successful. You're ready to digitize.  Make sure your target layer (the area layer) is current, with the drop-down menu from above.  With Tools, Digitize, launch the map editing tools which will be used by the mouse and tablet.

At any time you can save a ".map" file, which is very much like an .mxd file in ArcGIS; it will recreate your session if you crash!

The mouse/tablet button is a toggle which switches whether the mouse or tablet is active. F2 does the same thing.  Use the various options with the digitizer just as you would when using the mouse.  To add or split a feature, use the green plus sign, to merge, the blue arrows. To save edits, use the green light; to discard edits: red light.  When you use the mouse/tablet toggle, the cursor will change shape to show you which is active. Button 1 is like the left mouse button, button 2 is right-click (undo).

• Edit, Preferences will allow one to change the snap tolerance in pixels, with a default of 7

ADDING DATA
When you 're done, you're ready to add the data to the layer.  See the attribute table with the button just to the right of the "current layer" dropdown menu.  If you have many polygons, you may not know which row in the attribute table corresponds to which polygon. To determine which is which, go to the map, use the blue pointing finger from the toolbar, and select a polygon.  Back in the attribute table, that row will be selected (a box in the very left column).  Type in your information for that polygon, and repeat for all polygons.

Using Tools, Export, export each new layer to a shape file (take care not to export "Selected Only.").
 

THE ASSIGNMENT
Spring 2004
Find a U.S. (lower 48) map with a google search or any other resource and create a layer that is likely to be useful in the indexing assignment.

Register your map using the instructions above.  Digitize your layer and add your attribute data.
Export to a shape file, and give me (1) the paper map, and (2) the shape file(s).  These will be several (probably 3) files with the same first name.
Create a file with Notepad called "filename.txt" which explains what you've done.  Give me that with the shape file(s).
And create an image that you'll put on your web site, with explanation of what you have done for this assignment.

• You might do a screen capture, or save as a .jpg.

• Use the editing tools as you did last week to touch up your map in case there was a small problem as you digitized.
• Add a Choroplethic fill with the button with the red/green/blue triangles.  If you choose a text field, every unique value will be a hue.
• You can use the scatter dot map or the proportional symbol map too, if you'd like.  They're pretty straightforward.
• Add a legend with the top button that looks like a legend.  If you double-click the legend you can "stick"it to the map.  Otherwise it won't export as a .jpg although it will screen capture, of course.
• Add labels to your polygons with the "tag" icon at the top of the screen.  I'd use "range" for my map of rainfall.
• Change the order of the layers (put states on top?) if you want to, with the Map Layers icon just right of the math symbols.

REGISTERING AND DIGITIZING IN ARCMAP
It doesn't work yet.