ieijing 2008 
1201 
TOWARDS A NEW PARADIGM FOR HIGH-RESOLUTION LOW-COST 
PHOTOGRAMMETRYAND REMOTE SENSING 
I. Colomina, M. Blâzquez, P. Molina, M.E. Parés and M. Wis 
Institute of Geomatics 
Generalität de Catalunya & Universität Politècnica de Catalunya 
Parc Mediterrani de la Tecnologia 
Av. del Canal Olimpie s/n, Castelldefels, Spain 
ismael.colomina@ideg.es 
KEY WORDS: calibration, INS/GPS, orientation, photogrammetry, remote sensing, trajectory determination, UAV. 
ABSTRACT: 
Current mobile primary data acquisition systems can be grouped in three main categories: terrestrial, manned airborne and satellite 
borne. This paper discusses whether Unmanned Aircraft Systems (UASs) together with the appropriate sensing and navigation- 
orientation payloads can constitute a new, fourth data acquisition paradigm of the high-resolution and low-cost type. For this purpose, 
and based on practical experience gained at the Institute of Geomatics (IG), some fundamental issues of UAS-based photogrammetry 
and remote sensing (PRS) are reviewed; from the geomatic aspects of navigation and orientation, to the manifold of already existing 
applications and to various regulatory initiatives that the main aviation authorities are conducting. The paper identifies technical 
challenges and advantages specific to UAS-based PRS and concludes that, beyond the technical aspects, one key issue is the 
integration of UAS in the civilian non-segregated airspace. 
1. INTRODUCTION 
A typical UAS consists of an Unmanned Aircraft (UA), a 
Control System (CS) —usually a Ground Control System 
(GCS)— and a communications data link between the UA and 
the CS. In civilian applications, the vast majority of UAs are 
equipped with sensors and perform some form of remote 
sensing. The term and concept of UAS have been recently 
introduced to replace those of Unmanned Aerial Vehicle (UAV) 
which is just a component of an UAS. 
UAs can be categorised in terms of weight, altitude and range, 
and other criteria. According to weight we have micro UAs 
(less than 2kg), mini UAs (2 to 8 kg), small UAs (8 to 25-30 kg) 
and tactical UAs (25-30 to 400 kg). Figure 1 shows an example 
of a small UA for PRS applications. (Sometimes, UAs 
weighting less than 150 kg are also referred to as small UAs.) 
According to altitude and range we have Low Altitude Long 
Endurance UAs, Medium Altitude Long Endurance (MALE) 
UAs (5.5 to 18 km), High Altitude Long Endurance (HALE) 
UAs (above 18 km) and others. UA classification is of the 
utmost importance for worthiness and certification issues and a 
current hot topic in the aviation community. The above 
categories are not comprehensive, given just for the sake of 
clarity and may easily change in the next months. 
communications, advertising, media, audio broadcasting and 
meteorology. 
Requiring no on board human pilots has advantages and 
disadvantages. The fundamental advantage of UASs is that 
they are not burdened with the physiological limitations and 
economic expenses of human pilots. As a result, UAs use to be 
cheaper, smaller and lighter than their manned siblings. UAS 
operations are therefore far less expensive (20-30 /hr for a 10 
kg payload) than any manned aircraft and far more 
environmentally friendly (generate less C0 2 and noise). 
Furthermore, there are areas and circumstances where manned 
aircrafts cannot be flown and where unmanned systems can, 
like low altitude flights. 
The fundamental disadvantage of UASs is that they do not 
benefit from the sensing and intelligent features of human 
beings and, therefore, they are less able to react to unexpected 
situations. Mainly because of this, the usage of UASs is not yet 
sufficiently regulated by the civil aviation and security 
authorities. This is a major barrier to the development of the 
UAS natural market. Other, derived, issues are those related to 
communication links (reliable, long range, low weight, out of 
line-of-sight, sufficient bandwidth), collision avoidance and 
homeland security. 
UASs date back to the 19th century and modem UASs date 
back to the Second World War. Historically, UASs have had a 
strong military presence for scouting and attack missions since 
their use in the battlefield involves no risk of loss of human life. 
The dominant role of the defense and espionage industry 
notwithstanding, the civilian applications and their overall use 
have expanded dramatically over the past years. The statement 
can be easily proven by a quick Internet web search. Among 
their many uses, we can mention Earth observation and aerial 
surveying, precision agriculture, environment monitoring and 
sampling, general scientific research, surveillance, 
The above mentioned advantages and the availability of the 
Global Positioning System (GPS), together with the 
unstoppable miniaturization of computer and sensing 
technology, have calledthe attention of many professional 
communities to the use of UAS. In this paper we explore the 
feasibility of high-resolution airborne PRS with UAS.