This exercise will demonstrate how to create new data by drawing it from scratch, sometimes known as digitizing. New data files are created first in ArcCatalog and then “edited” in ArcMap. This will be explained more as we go through the exercise.

First, open ArcCatalog. The format is similar to that of Windows Explorer windows (or Folder view).

A quick explanation of ArcCatalog: similar to a file cabinet, it can show you all data as it relates to ArcMap and where it is at. Only data files that are supported (or able to be used) by ArcMap will be shown, so a PowerPoint or Word document will not be shown.

On the left hand side you will see the directory of the drives, folders, and data contained within.  

On the right hand side you see a box with 3 tabs: Contents, Preview and Description. Contents will illustrate what folder, files, data are in the highlighted object from the left hand side.

Preview will show you what individual data files look like, either in tabular format:

Or in a geogrpahical format (notice the same “california counties” data is shown in both screenshots)

The Description (previously called Metadata) tab provides data about the data. A separate exercise will explain more in detail about that later.

Now that you know how data is illustrated and categorized in Catalog, let’s make some! Navigate to your course folder and right-click on it

With the box that comes up next, point your mouse arrow overwhere it says New, then single left click where it says Shapefile.

With the next dialog box that opens up, Type “ParkingLot” where it says Name:Then where it says Feature Type:, use the drop down arrow to select Polygon

Next you will see that in the same box under the heading Spatial Reference, it says “Unknown Coordinate System”, we are going to change this.

Click Edit…

MultiPoint and MultiPatch are a collection of points and polygons that when looked at geographically have more than one feature, but looked at in a table, they are actually one feature.

Click Select…

Then, as was done in the exercises from ArcMap, we will select the Geographic Coordinate Systems folder by double clicking it.

Then again click the folder for North America

Then click NAD 1983.prj (North American Datum)

Click OK

Now you will see that the “ParkingLot” shapefile has a spatial reference. Now click OK

Congratulations! You have just created a polygon shapefile which you can see by looking at the left hand side of the catalog.

You will notice though if you click on the Preview tab, there is nothing showing, that’s because the data filestill has to be “edited” in ArcMapwhich is what we will do next.

Creating a spatial reference is similar to assigning a map’s coordinate system.

Open ArcMap and create a new map saving it in your course folder, remember to set as relative path. Now set the maps coordinate system to NAD83 as we have been doing. (Refer to previous exercises if you forgot how).

Add Data, navigating as you did in Exercise 2, to the “Phx_Low03_Ortho” folder; add in the two .tif files.

Add Data again, this time navigating to the new “ParkingLot” shapefile in your course folder.

Your ArcMap screen should look similar to this as far as what data is on the map:

If it doesn’t, then things went terribly wrong and somewhere in the distance a butterfly cries… but don’t worry…

You notice that “ParkingLot” has a color assigned to it, but you don’t see that anywhere on the map; remember the file was created but the actual data needs to be edited.

Zoom in on the large parking lot on west side of the street:

Next, make sure your Editor toolbar is visible by right clicking any area where your tools are:

This will show you a list of toolbars that are available to be displayedin ArcMap; if there is no checkmark next to Editor, simply highlight, and click once. You should then see your Editor toolbar displayed:

Next click on the dropdown arrownext to where it says Editor; this will promptthe box where you highlight and click whereit says Start Editing.

You will receive a message letting you knowthat you are about to edit in a different coordinate system, click Continue

If you have more than one file you are going to edit, and those files are in different locations, make sure you select the correct file. ArcMap can only “look at” one location at a time during an edit session.

Look at the Editor toolbar now, all flashy and bright like it’s going to the casinos with you tonight:

Also you'll notice that on your screen on the right side a box appeared that is titled Create Features. It's in this box that your selecting what feature (ParkingLot) you will edit.

Click in the Create Features box on ParkingLot to select it as the editable feature.

Notice now that a box appeared underneath called Construction Tools and has 6 options. These allow you to use distinct drawing tools to create (and modify) your data.

Click on the Polygon tool.

Your pointer has changed to a crosshairs symbol

Where you click on the map will create a vertex for your polygon. Your task it to outline the parking lot.

Choose any corner of the parking lot you want to start at and click once to create a vertex,then at the next corner or turn, click again to create another vertex.

A quick note: When you select Editor and Start Editing you are establishing what is called an “Edit Session”. During an Edit Session you may do different tasks, which can include creating, modifying the shape or attributes, and others.

In the illustration below, the aerial imagery was brightened to show the series of vertices as the shapefile was being created

To complete the sketch after you place your last vertex, right click to bring up a context menu and then (left click) on Finish Sketch

Air Quality and GIS

A point source can be represented by a point feature

An area source can be represented by a polygon

Your drawing should look somewhat like the following

To complete and finish, click the Editor dropdown arrow

Then click Save Edits,Click again on the Editor arrowThen click Stop Editing

Great job! You’ve just created a file from scratch, assigned it a coordinate system and then drew a new feature to be assigned to that file (a shapefile). Save your map.

But, unfortunately…. The parking lot has changed due to construction, and it is now your task to edit the polygon accordingly.

Remember that when you select Editor and Start Editing you are establishing what is called an “Edit Session”. So now we are going to start an Edit Session so we can edit, by modifying, the existing polygon.

Let’s do that. Click Editor Start Editing (as before, click continue at the warning prompt)

By default, your mouse pointer should have turned into the “edit tool” if not, go ahead and click on it. With your edit tool, double click anywhere on the parking lot feature you just drew. You’ll notice that now you can see the green vertices, and one red one; if not click on the drawing (feature) again. Notice that by double clicking, it selected (seen by it being depressed) the Edit Vertices function and also brought up the Edit Vertices toolbar

We are going to remove thesouthwest corner to makeroom for a fountain.

The final parking lot will look similar to this

At this point, you may want to read “How I did it” on the next page, because your drawing and preference of steps may be different from mine.

On the Edit Vertices toolbar, click on the Delete Vertex tool.Click on any one of the vertices in the southwest corner to delete it.If you did not click on a vertex directly, you will have to reselect the Delete Vertex tool.

Depending on how many vertices you created when you drew it, deletehow many is necessary to accomplish the task. You can also move a vertex by using the Modify Sketch Vertices tool.

In case you need to insert a vertex, use the Add Vertex tool and click anywhere on the perimeter, as before, if you do not click directly on a line, you will have to reselect the Add Vertex tool.

How I did it, your process may differ

I used the Delete Vertex tool to accomplish the following

I deleted this vertex, then the 2 to its right (east).

Then I moved this vertex over to the west boundary of the parking lot

So that it looks like this

If you like and/or have a chance, play with the other editing tools (Reshape Feature & Cut Polygon Tools) to see how you can use them to accomplish the same tasks.

Then I clicked on Editor drop down Arrow, Then clicked on Save Edits, Clicked again on the Editor drop down Arrow, then clicked on Stop Editing

So my final product looks likeremember yours may lookdifferent, the importantthing is you know how to edit the shape of the feature.

Save your map.

One final work with Editing. This concept applies to the attributes of the features. The attributes provide information about the data; it can be names, measurements, label details, or anything else that you want to have linked to the feature. However, this information can change and should be updated.

For this next portion, let’s begin by once again starting an Edit Session.

Now, in the Table of Contents right-click on “ParkingLot”

Then highlight and left-click on Open Attribute Table

Notice in the field headers there are 2 in a box of gray and 1 in a box of white. The attributes in the gray column cannot be changed, however ones in white can be. Unless you are in an Edit Session, all the field headers will be grayed out

So click on the field where the 0 is, type in 32 and press Enter on your keyboard.

This same process can be duplicated to update other fields as applicable in other data sets.

Once again, save your edits, stop editing, and save your map.

Congratulations again! You have just successfully edited the physical appearance of a feature as well as changed some of the information about the feature.

Fields, just like in Excel, can be restricted to certain types of values such as numbers, text, dates, etc. So some values can be only changed to a restricted format-number to number, date to date…