El ayuntamiento de Madrid abre al público la Web de Vuelos

Madrid City Hall launches a public web site containing flights and orthoimages
of the urban area.
The project was carried out using the state of the art technology which allows a detailed
visualization with a very high quality, accuracy and 3D stereo.



Leading edge technology was used
Madrid is the first city in Spain and one of the first worldwide in getting a high resolution true ortho
(9 cm). Unlike classic ortho, it has a perfect geometry both on the ground and on the roofs making a
perfect match in the rooflines.
The data is open to general public through the internet.
Madrid city council has recently contracted a flight over the urban area in order to get aerial images
and orthophotos. The companies involved in this project (which are Microsoft/Vexcel, Azimut and
Sigrid) used the state of the art technology in photogrammetry. Microsoft/Vexcel made available its
technology which is being used in its project Bing Maps. In particular, the Ultracam Eagle, was the
selected photogrammetric camera which allows to perform a high definition flight, with high quality
and without interfere air traffic Barajas Airport, and the software to process the images and generate
the DSM, classic and true ortho was the Ultramap 3.0. Azimut carried out the photogrammetric
flight and the Spanish company Sigrid was the responsible for the image processing and also has
contributed with its technology StereoWebMap®, which allows the posting of photogrammetric
flights throughout the Internet, and its visualization both, 2D and Stereo 3D.
Orthophotos are aerial photos which have been geometrically corrected taking into account the
displacement which occurs due to the different height in the terrain, so every point in the image is
moved to the right position. However, with the traditional algorithms (Classic Ortho), this principle
is not totally true and it only works when the points are on the ground, if the points are located on
building roofs they are displaced from the correct position as they are higher than the ground. Some
buildings facades parts remain visible and some street parts are occluded by buildings.
These problems are solved using a much more complex and advanced methodology called True
Ortho. However this technology has not been used widely due to its complexity and its high. In this
project, together with a Classic Ortho of the city of Madrid, a True Ortho was also produced.
Therefore, Madrid becomes the first city in Spain and one of the first worldwide to have a high
resolution True Ortho (9 cm.).
1: Comparative Classic and True Ortho.
However, in addition to the classic and true ortho, there are other important products which may be
of interest to both: public-private organizations and citizens. Among these products, we can
highlight:
 Colored point clouds (16 points / m²). These point clouds are the starting point to build up
a precise 3D city model or generate more detailed digital models of buildings of interest.
2: Colored point cloud area Royal Palace

Digital Surface Model (9 cm)
Such a high density means that we are able to know the altitude above the sea level for each
one of the 9x9 cm cells (about the size of a credit card). It is an impressive improvement on
the resolution available to any municipality in Spain and much better than the previous
resolution which was available in Madrid (100 cm). The height information in conjunction
with the ortho is very useful for many applications such as: phone antennas dark areas
detection, best location for solar panels on roofs, 3D city models, emergency and hazard risk
evaluation, etc.
3: Digital model of textured surfaces

Multi-view. One of the project requirements was to have a high overlap (80-80). That
means that each point of the city of Madrid is visible from an average of 25 different photos.
Such a high number of point of views can be very useful for implementating municipal
inventories (sewers, streetlights, benches, etc.).
4 Foster Tower viewed from different frames.

Near Infrared Channel. In addition to the channels which are visible by the human eye
(red green and blue), the images also contain near-infrared. The information provided by this
channel is useful for environmental issues, trees identification, vegetation status, etc.
5 Botanical Gardens real color and false color.

Viewing stereo 3D flight through the Web. The 3D view in stereo adds major advantages
since it allows a much easier identification of elements and very precise measurements. With
the data on the Web, any user with a standard computer and anaglyph glasses (one red and
one blue glass) will be able to see any building in the city of Madrid in 3D stereo. In
addition, a lot of applications can be developed on top of that. For instance, anyone with a
3D Smart TV could visualize and walk through any area in the city of Madrid in 3D stereo.
At the same time, he could generate videos and upload them to YouTube 3D.
Professional users, with appropriate hardware, can view the buildings in true stereo and do
measurements with a lot of accuracy. Examples of use: After an emergency call to the fire
department, technicians can compute the height of the affected building very precisely and
thus know if the height of the stairs or pressure hose will be enough to reach the roof. It is
also possible to evaluate if the neighborhood could be evacuated through some adjoining
terrace, etc.
6 3D image building in Madrid with point coordinates as
Information on this project can be found: http://madrid.sigrid.es
The total amount of data which was generated taking into account each phase of the project was
more than 20 TB information. The development of technologies and applications able to
automatically analyze and explode this data would have a perfect fit within the strategic objectives
of the program I + D + i of the European Union Horizon 2020, in particular in projects related to
Big Data or Smart cities.
The Government Department of Planning and Housing of the City Hall of Madrid, encourages
all potential users (both public and private) to make use of the data generated in this project
for whatever they like.