You have just been given an aerial photograph that is not registered to real world coordinates. How do you display the aerial with other data layers that have real world coordinates (I.e. map projection)

In this lesson, you will learn how to:

Register an aerial photograph to vector data

Open an orthophoto that is already registered

Lab1: Aerial Photographs

Scanning:

Automated method to extract data from maps & photographs

The image to the left is a scanned image. The original photograph is placed in a scanning device; a photoelectric cell or “eye”passes over the photo or document andrecords any mark on the photo.

The resulting data is stored in pixels or cells.

Each cell may consist of a defined value.

The scanned image is in Raster GIS format.

Satellite imagery maps can be easily scanned since the output is diplayed in pixels or cells.

Landsat satellite image

Detailed satellite image view

To overlay an aerial photograph, it must be registered to a reference:

Select control points on the aerial photograph

Select the corresponding locations on a locationally referenced vector data layer.

Register an Aerial Photograph

a

b & c

b & e

f

d

g

Selecting control points on the aerial and the vector layer:

Scanning is useful:

Scan & register the image

Use heads-up digitizing to capture the spatial objects

In this example,

1. The aerial was scanned & registered (control points were known).

2. Trace or heads-up digitize the river as a polygon

You are now ready to begin MapInfo Exercise- Lab 3 Aerial Photographs. The main objectives are:

• Register an aerial photograph to vector data

• Open an orthophoto that is already registered

• Begin exercise- lab 3