Presentation on theme: "With support from: NSF DUE-0903270 Prepared by: in partnership with: John McGee Jennifer McKee Geospatial Technician Education Through Virginia’s Community."— Presentation transcript:
With support from: NSF DUE Prepared by: in partnership with: John McGee Jennifer McKee Geospatial Technician Education Through Virginia’s Community Colleges (GTEVCC)
To learn techniques for generating new spatial features in a layer. To learn techniques for including non- spatial data in your final Map Layout (for example, graphs and reports)
Working with raster data Digitizing from digital imagery Adding X,Y data to a map document Buffering layers Creating a report Creating a graph Adding a graph to a Map Layout
Method of converting information from one format to another using a trace methodology. Traditionally, digitizing has meant the creation of a spatial dataset from a hardcopy source such as a paper map or a plan.
The “old way”
Uses on screen digitizing, usually with an aerial photograph in the “background” You are no longer bent over a digitizing table (hence “heads up”). ArcGIS provides several tools to support editing…
Most vector spatial data has been digitized from paper maps and aerial or satellite photographs. Digitizing data involves placing a map or photo on a digitizing table and tracing features. – Heads-up digitizing is digitizing on your monitor, not a tablet.
Features can also be digitized without tracing. – ArcGIS has several tools for creating circles, rectangles, curves, and other shapes of exact dimensions. You can specify angles and lengths of line segments. You can specify that line segments be perpendicular or parallel
Points are features with no parts. – They can be digitized with a single click. Lines have a beginning and ending, and often change direction. Polygons are lines that return to their origin.
The points where a line begins and ends is called an endpoint. The points where a line changes direction or is intersected by another line are called vertices. The segments between vertices are called edges. Endpoints (in red)Vertices (in green) Edges Digitized Line
A feature that has its vertices, edges, and endpoints visible. Once the feature is saved, the vertices, edges, and endpoints disappear and it is no longer an edit sketch.
All digitizing is done during an edit session. –T–Task: operation you want to carry out –T–Target: layer in which features are being digitized –T–Tool: software function for completing the task
9 Tools for drawing edit sketches – Grouped on a drop-down tool palette called the Sketch Tool Sketch Tool
Creates new features within point, line, and polygon layers Sketch Tool
Lets you define the location of the next vertex by clicking two points; the new vertex is placed at the midpoint of the line between these points. – Example → Roads Midpoint Tool
This tool lets you create a point or vertex at the intersection of two distances from two other points. – Creates two circles based on two distances and finds two possible intersection points where the primary can be placed. Distance-Distance Tool
Allows you to create a vertex using a distance from a known point, plus a direction from a known point to define a bearing line. – For example, a pole might be located at a specified distance from the corner of one building, and at a defined angle from the corner of another building. Direction-Distance Tool
Helps you create new segments that follow along existing segments. – Essentially creates parallel line segments Trace Tool
Adds a segment that is tangential to the previously sketched segment. – This tool is practical when sketching rail lines in which the curves are nearly always tangential to the previous segment. Tangent Curve Tool
The Arc tool helps you create a segment that is a parametric (true) curve. Arc Tool
The Intersection tool creates a vertex at the place where two segments would intersect if extended far enough. Intersection Tool
Allows you to specify the start and endpoints of the curve, then define a radius for the curve. – This is particularly useful in sketching cul-de-sacs, where the beginning and ending points of the arc, as well as the radius of the cul-de-sac, are known. Endpoint Arc Tool
You can undo digitizing mistakes with the Undo button on the Standard Toolbar. Or you can use ctrl-z