PHOCAD PHIDIAS

Key Applications

PHIDIAS is a complete solution for close range photogrammetric applications:

• 3D – Models of buildings
• As-built-models of industrial facilities
• Deformation analysis
• Stereo Aerial Photogrammetry
• Data collection for GIS
• Reconstruction of accidents and crime scenes
• Photo rectification
• Visualization

Key Advantages

3D point clouds, which are captured with a Laser Scanner, can be used in combination with photogrammetric images. On the condition that the coordinate system in both cases is identical, the point cloud replaces the missing third dimension in the images. By this means a 3D single image measurement is possible. The combination of both procedures leads to several advantages:

• Small details of the scanned object beyond the scanner resolution, which are normally lost, are visible in the high resolution photogrammetric image. Wrong interpretation can thus be avoided.
• Time-consuming stereo measurement can be replaced with mono image measurement.
• Single photogrammetric images can be oriented separate without taking notice of the angle between the photographs.
• Orthophotos can be produced directly. The third dimension is already known.

PHIDIAS processes digital images which are loaded into the views of MicroStation in order to evaluate them. The user carries out the geometric evaluation by means of the digital images loaded on the screen without being restricted by the operating possibilities of MicroStation. This means, for example that the command ‘place smartline’ can be activated and executed in MicroStation as normal. PHIDIAS intercepts the placement of points in views if an orientated image is loaded and makes sure that the element is being drawn considering the photogrammetric orientation parameters.

The obtained evaluation result is superimposed as a drawing on the photographs. The embedding of the photogrammetric element PHIDIAS in MicroStation presents many advantages to the user such as:

• The extensive selection of commands in MicroStation for the generation and processing of plans is at the user’s disposal for the photogrammetric evaluation. The efficient generation of drawings is for example supported by basic functions such as copy, move, mirror etc.
• As a result of the superimposition of the drawing on the images, the user can see at a glance whether the evaluation on the screen is correct and complete. Thus, the user is able to correct many errors already during the recording, which occurs especially when measuring three-dimensional, complex objects.
• MicroStation supports special tools such as ‘dimension driven cells’. With this, geometric elements with the same basic structure (e.g. views) can be filed in their own libraries and pasted during the photogrammetric evaluation adjusting the respective dimension. The measuring tasks are thus mainly reduced to the positioning of the objects.
• In the process of the evaluation, surfaces and volume elements can be generated directly. In comparison to the pure wire frame model, this model offers multiple visualization possibilities in connection with the powerful rendering-tools from MicroStation.
• If surface and volume elements are generated during evaluation, sectional drawings can afterwards be generated automatically from the measured objects. The cutting plane can be placed anywhere in space.
• In order to link specific alphanumerical information with the geometric drawing data, the user can refer to external databases by means of an interface. Thus, specific data such as the condition and kind of material etc. can be recorded simultaneously with the photogrammetric evaluation and then stored in a relational data base. Other MDLApplications like GeoGraphics, TriForma or PlantSpace can also be used together with PHIDIAS.

The user who is familiar with MicroStation usually does not have great difficulties to carry out photogrammetric evaluations with PHIDIAS. The handling is quite similar to the work with MicroStation.

Further Information

Download the PHIDIAS PDF brochure here, and an overview here.

For more information, please visit www.phocad.de.

3D model generated from photographs and laser scanning data (Image courtesy of eta AG)	3D model generated from photographs and laser scanning data

Photo rectification	Detailed modelling of buildings

3D model and laser scan data (Image courtesy of eta AG)	Bridge modelling using point cloud overlayed onto photograph