Geo . Referencing

Geography

1. K.L.E. Society’s SHRI KADASIDDHESHWAR ARTS COLLEGE AND H. S. KOTAMBRI SCIENCE INSTITUTE VIDYANAGAR, HUBBALLI-580031 (Karnataka State) Accredited at ‘A+’ Grade with 3.28 CGPA by NAAC in 4 th Cycle Office: 0836-2372097 Website: skahsk.com E-mail: [email protected] DEPT. OF GEOGRAPHY B A VI Sem 2023-24 Name of Faculty : Dr. B.R.Jarakunti Name of Paper : Practical Paper 2 – GIS for Map Making Topic : Geo-referencing by toposheet

2. Georeferencing Georeferencing  is the process of assigning locations to geographical objects within a geographic frame of reference. It is fundamental to geospatial technologies in general, and geographic information system (GIS) in particular.

3. Definition Georeferencing is the process of aligning satellite imagery or other types of maps with real-world geographic coordinates. In simple words, it involves taking an image of the Earth's surface, and placing it accurately on a map of the same area. To georeference an image, you need to identify a set of ground control points on the image, which are known locations on the Earth's surface with known geographic coordinates. These ground control points serve as reference points to align the image with the actual geographic coordinates of the area.

4. Types: Depending on the spatial resolution in effect, georeferencing mechanisms can be generally classified into metric georeferencing and indirect georeferencing 1)Metric georeferencing , also called continuous georeferencing , is coordinate-based. Every location on the earth surface can be specified by a set of values (coordinate) in a coordinate system. Metric georeferencing underpins  GIS databases , which contain collections of spatial features referenced by coordinates . 2) Based on existing metrically georeferenced GIS databases, indirect georeferencing methods retrieve the metrically georeferenced locations through attribute data. For example, the attribute could be the name or index associated with a location.

5. Key Benefits and Uses: Creating Accurate Maps : Essential for purposes like urban planning, disaster readiness, and environmental auditing. Change Detection Over Time : By comparing historical and current georeferenced imagery to pinpoint environmental or urban shifts. Spatial Data Integration : Merging maps with demographic stats, climatic conditions, or geological data for enhanced regional insights. Natural Resource Management : Enabling the monitoring of forests, agricultural expanses, or hydric zones through dedicated analysis of georeferenced images.

6. What is mobile LiDAR ? Light Detection and Ranging ( LiDAR )  is a technology that uses light beams from a laser to collect accurate measurements of an environment. Traditionally, LiDAR for mapping is found in terrestrial laser scanners and has formed part of a surveyor’s toolkit for the past few decades. As the name suggests, mobile LiDAR is a way of capturing 3D data with more mobility, for example handheld or via  UAVs  and  vehicles.

7. Methods of Geo-referencing 1. Matching Reference and Control Points Using a GNSS receiver, a minimum of 3 reference points are captured in the scan area. These points are known coordinates and a survey pin often identifies them . 2. Reflective targets Like the method above, georeferencing using a reflective target requires a minimum of 3 control points using GNSS. Placing the targets on the known control points gives users the freedom to move through their data without stopping. 3. Using GPS on the move The third and final way to georeference mobile LiDAR data is via a backpack and GNSS receiver. By capturing live GPS coordinates during a scan and matching the scanning and GNSS trajectories, you can simply georeference the resulting data.

8. Geo-referencing Importance 1) Crowdsourcing and memory   georeferencing  is distinct from mapping as an academic crowdsourcing task. Whereas mapping refers to the creation of new geographic data (as do users of OSM), georeferencing is the process of adding accurate world-grid coordinates to content that already exists. 2) GIS Methods and Techniques Location plays a significant role in  geography  and geographic  information systems  (GIS).  Georeferencing , defined as the general process of relating information to a geographic location, is an important concept in GIS (Hill, 2009).

9. 3) Transport and Sustainability 4) The Geography of Innovation Based on the  economic geography , paradigm is a new emerging field that can shed light on pathways to achieve transport and sustainability by  georeferencing  innovation clusters across time. Georeferencing involves assigning coordinates to pixels of maps. 5) Measuring Location A system for accurately identifying location on the surface of the Earth is an essential component of any GIS representation. The Meridian Conference of 1884 established latitude and longitude as the universal standard for  georeferencing , based on measurements from the Greenwich Meridian and the Equator.

10. 6) Relationship of Remote Sensing to Other Geographic Information Technologies While many remote-sensing operations involve visual interpretation of imagery, digital image processing is commonly employed for classification and other analyses. In addition, global positioning system (GPS) technologies are frequently used to assist with  georeferencing  remotely sensed imagery to allow points on an image to be associated with locations on the ground or with other georeferenced data sets.

11. 7) Geolibraries A geolibrary is a digital library that, in addition to being searchable by traditional methods, stores information in a format searchable by geographic location; such data are thus georeferenced . In principle, a geolibrary need not use online techniques for indexing or storage of content, and paper-based map collections with appropriate catalogs have existed in libraries for many years.

12. 8) Spatial processes: mapping and georeferencing Mapping, in the typology of Dunn and Hedges (2012), refers to the process of creating a spatial representation of one or more information assets. This could be information about the real world as it is experienced and/or observed; for example, crowdsourced web mapping has become for many people an extremely important part of their daily web activity, again as a result of the rise of mobile technology, and it can involve the collaborative creation of map data from scratch, as in the OpenStreetMap initiative.