The digital orthophoto process transforms a vertical aerial photograph into the equivalent of a traditional map. Yet it retains the advantages of a photograph—visually displaying actual cultural and land features, and the built environment, rather than representing those features using symbols and lines.The quality of a digital orthophoto is dependent upon the quality of each step in the process. For example, it is essential to start the process with good imagery and accurate input data, rather than proceeding, and trying to repair flawed imagery later. Because of our attention to quality outputs, Central Coast Aerial Mapping Inc. will provide you with accurate and visually appealing orthophotography, and do so in your preferred data format.
Digital Terrain Models (DTM)
The digital terrain model (DTM) can either come from an existing source or it can be developed from the aerial photography. The aerial photos are taken using a stereoscopic camera, with which two pictures of a particular area are simultaneously taken, but from slightly different angles. The overlapping area of the two resulting photos is called a stereo pair. Using a computer called a stereoplotter, the stereo pair can be viewed as a single image with the appearance of depth or relief. Ground control points are established based on ground surveys or aerial triangulation and are viewed in the stereoplotter in conjunction with the stereo pair. In this setting, the image coordinates of any (x,y,z) point in the stereo pair can be determined and randomly selected and digitized. These points, in conjunction with 3D breaklines and control points, comprise the data points for the DTM. The accuracy of the final digital orthophoto will depend in large part on the accuracy of the DTM.
UltraCam X Digital Camera
Vexcel’s new UltraCamX provides the same obvious advantages over film cameras as the UltraCamD, but has superior specifications and extended capabilities. The data flow is simpler, the technology is more robust, and image formatting is the world’s most precise.
One of the most widely used of all maps is the topographic map. The feature that most distinguishes topographic maps from maps of other types is the use of contour lines to portray the shape and elevation of the land. Topographic maps render the three-dimensional ups and downs of the terrain on a two-dimensional surface. Topographic maps usually portray both natural and man made features. They show and name works of nature including mountains, valleys, plains, lakes, rivers, and vegetation. They also identify the principal works of man, such as roads, boundaries, transmission lines, and major buildings.The wide range of information provided by topographic maps make them extremely useful to professional and recreational map users alike. Topographic maps are used for engineering, energy exploration, natural resource conservation, environmental management, public works design, commercial and residential planning.We have the ability to compile full 3D mapping products in digital format. We utilize DAT/EM SUMMIT EVOLUTION digital photogrammetric workstations. Our mapping process consists of creating a DTM that consists of 3D breaklines and points. These methods facilitate the engineers to create surface models, hydraulics engineering, alignment and cross sections. Using a DTM (Digital Terrain Model) process, resulting in achieving high accuracy in development of a TIN (triangular irregular network). Our final map files can be delivered in an AutoCAD DWG or Microstation DGN format.
The 3D surface is approximated by a triangular mesh to reduce geometric complexity and to tailor the model to the requirements of computer graphics visualization systems. Our surface models are derived from the DTM which are generated from 3D points and breaklines. Surface models can be used for many engineering calculations such as hydrology, earth volumes and design.
Our RM-6 high resolution photogrammetric scanner can handle roll film or individual frame scanning. Motorized spools for automated film advancements makes project management efficient with the ability to handle multiple setups for jobs. Real time tonal correction offers superior image color and quality. Our scanning services offer consistent, high geometric accuracy without resampling.