ortoXpres

Photogrammetric flights are carried out to obtain information on the territory for different purposes, but this information is not obtained directly from the data captured, but from a derived product, usually cartographic. Well, the creation of this derivative product implies the processing and editing of the original data to achieve a certain quality and precision, which in turn supposes a significant time lag between the capture and the availability of the information.

In the case of orthophotos, despite having reduced their production time, although they present lags of months, and for some of their uses, immediacy is prioritized over quality, being necessary to visualize the data in a similar way to the final product but as soon as possible.

Even in some jobs, due to their context, a quality orthophoto is never generated, an intermediate solution being sufficient.

 

Alternatives

To cover with the immediacy necessary in some areas, or for comparison tasks, it would be possible to consult the original frames one by one, but their understanding and measurement is complex if they are not shown in a wider geographical context.

The ICGC orthoXpres service allows you to navigate on a continuous and georeferenced orthophoto (then it can be combined with another cartography), a few days after having flown from single historical frames, and although this orthophoto does not have the quality and precision of an edited one, its immediacy and continuity cover the current deficiencies in certain surveys.

 

Solution description

ortoXpres is based on a server that, in response to a WMS request, processes the original frames and returns an image, simulating navigation on an orthophoto. That is, the orthophoto does not exist previously, but is created on the fly.

To achieve this effect, any web viewer or application could be used, made to measure or compatible with the WMS protocol. In addition, as it is georeferenced information, it is possible to combine it with other cartography (cadastre, previous orthophotos ...) and make comparisons and analyzes, especially interesting when photos of different dates are available.

In all this process, executed in real time, in addition to the DTM necessary for rectification, aerotriangulat frames can be used, but this would imply a delay in their publication. In any case, the ICGC offers a wide catalog of frames, but it is also possible to upload others belonging to third parties (with the corresponding permissions).

This service allows the creation of several layers, organized by date or purpose (changes in urban areas, quarries, landfills ...), where only the information that is needed consists of, simplifying its use.

By working directly with the original frames, ortoXpres also allows for stereoscopic viewing using anaglyphs, as well as compositing with infrared where available.

The stereoscopic display, in turn, makes it possible to promote the customer by customizing the corresponding anaglyph glasses, if this were a goal.

The only limitation to be aware of in this solution is that effects such as duplication of bridges and reflections cannot be avoided. In quality orthophotos, these artifacts are edited manually.

 

Articles

• Explotació de les dades primàries: ortoXpres. A. Magariños, Revista Catalana de Geografia, 2009

 

Fulfilled projects

• www.ortoxpres.cat

 

Related applications

• Performing photogrammetric flights
• Generation of orthophotos