As discussed in the Basics module, digital orthophotos are very useful because of their map-like qualities. Because they're digital, they can be displayed and printed at various scales, leading to many variations of uses for them, both at state and local levels. And as technology improves so do the potential applications of DOPs.
DOP applications include urban planning for smart growth, environmental assessment, crop science,
agriculture, geology, soils science, watershed management, geography, landscape architecture, civil engineering, biology, and
pollution prevention.
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The accuracy and extraordinary
detail of DOP's allow users to visually evaluate their data for accuracy and thoroughness, to modify their data promptly, and even to
generate new files. An orthophoto can be used in a wide variety of geographic information systems and is an excellent cartographic
base on which to overlay any number of associated thematic layers for displaying, generating, and modifying planimetric data
or associated data files.
- Digital orthophotos used as reference layers
- Digital orthophotos used as land-based sources
- Digital orthophotos used for time change assessment
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Digital orthophotos used as reference layers
Digital orthophotos are great as reference layers because they provide a picture to correspond with the lines and polygons of other maps, making it much easier for people to understand. Interest in orthophotography continues to grow as departments realize the potential of applications. For instance, when the NAPP coverage of Wisconsin was completed in 1992, requests for DOP coverage increased rapidly. Agencies ordering coverage include: NRCS, USDA Forest Service, USGS, individual counties, regional planning commissions, and the Wisconsin DNR. The NRCS ordered coverage for several west-central counties, including both digital orthophoto quarter-quads and the individual county project coverages, for the purpose of revising the soil survey for compatibility with other maps.
For examples of projects utilizing orthophotos as reference layers, check out the following sites:
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Digital orthophotos used as land-based sources
Digital Orthophoto Quadrangle (DOQ) data are useful to government, academia, and the private sector in many disciplines. They are being used to provide geometrically correct, detailed images for deriving data for a wide variety of applications. And as an excellent geographic base data layer, DOQs may be used for many large-scale mapping projects such as: land and timber management, routing and habitat analysis, environmental impact assessment, evacuation planning, flood analysis, soil erosion assessment, facility management, and groundwater and watershed analysis. Application of DOQs to local and regional problems enables more intelligent assessment and management of available natural resources and the man-made environment. As the most current imagery available, DOQs provide an excellent benchmark to explore historical trends including urban growth, land use, and erosion.
Orthophotos are much more accurate and detailed than uncorrected aerial photography, leading to the better use of resources and more efficient project handling. In the case of natural resources, an inventory of natural habitat areas within a specified region can be produced using DOPs. The updates can be done directly by overlaying parcel coverage and comparing old and new imagery. Areas of additional surverying can be identified on the DOPs and directed to the correct office. This eliminates the need to survey the entire region, decreasing the update time by 4 or 5 days.
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Digital orthophotos used for time change assessment
The ease of updating digital orthophotos is a major advantage over traditional methods. Because of the unliklihood of a drastic change in landscape, the original DEM can be used for an existing study region. New aerial photography is flown and the existing surface is used to support correction. Since the update procedure is rather simple, consistent analysis of the region can be accomplished.
Another important aspect of DOQs is the ability to link their attributes with others, such as remote sensing and GIS layers. By doing this, new applications like a 3-D GIS can be derived to accurately identify a geographic location. Currently, software is being developed to facilitate the interactive visualization of high-resolution 3-D data of many differerent fields. Large amounts of data from DEMs, orthophotos, satellite images and vector layers will be able to be processed relatively quickly and viewed as high quality representations of reality.
Developments, such as 3-D visualization, will have a major impact on the potential of DOP applications. Models for various fields, including business, population, and biological application, will be paired to images on a point or polygon basis. This will enhance the use of aerial photographs for historical and current applications, which will improve hypothesis testing. Landscape changes will be determined by the development of stereoscopic images at similar resolution for viewing and analysis.
For additional examples of applications of DOQ's, visit the following sites:
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