like generation of orthoimages, updating of topographic map data bases and generation of digial terrain models.The book includes a preface and four articles which deal with the automatic georeferencing of aerial images. The georeferencing or orientation of aerial images is the first step in mapping tasks l. The articles are the written contribution of an seminar, held at Aalborg University in October 2002. The book includes a preface and four articles which deal with the automatic georeferencing of aerial images. Viewers can adjust the transparency with the slider bar on the top right, view the historical map as an overlay on terrain or satellite images, or click ‘Earth’ to switch into Google Earth mode and see 3DĪutomatic Georeferencing of Aerial Images by Means of Topographic Database Information To offer some examples of georeferenced historical maps, we prepared some National Topographic Series maps hosted on the University of Toronto Map Library website courtesy of Marcel Fortin, and we overlaid them on a Google web map. In cartography this is known as rubber-sheeting because it treats the map as if it were made of rubber and the control points as if they were tacks ‘pinning’ the historical document to a three dimensional surface like the globe. These are used to correct the distortions and inaccuracies found in many historical maps and stretch the maps so that they fit geographic coordinates. Entering control points in a GIS is easy, but behind the scenes, georeferencing uses complex transformation and compression processes.
The built and natural landscapes change over time, and it is important to confirm that the location of your control points — whether they be houses, intersections, or even towns — have remained constant. Georeferencing a historical map requires a knowledge of both the geography and the history of the place you are studying to ensure accuracy.
#Georreferenciamento quantum gis software#
The technique uses a series of control points to give a two-dimensional object like a paper map the real world coordinates it needs to align with the three-dimensional features of the earth in GIS software (in Intro to Google Maps and Google Earth we saw an ‘overlay’ which is a Google Earth shortcut version of georeferencing. Georeferencing is required for anyone who wants to accurately digitize data found on a paper map, and since historians work mostly in the realm of paper, georeferencing is one of our most commonly used tools.
#Georreferenciamento quantum gis how to#
Directory of Open Access Journals (Sweden)įull Text Available In this lesson, you will learn how to georeference historical maps so that they may be added to a GIS as a raster layer.