FROM ANALOG TO DIGITAL AERIAL IMAGEPRODUCTION. 
EXPERIENCES FROM NMA-IMAGE-PRODUCTIONS BASED ON EU-TENDER. 
John kamper 
National Survey and Cadastre - Denmark, Rentemestervej 8, DK-2400 Copenhagen NV, Denmark - 
jk@kms.dk 
KEY WORDS: Digital Cameras, Photogrammetry, Remote Sensing, Production, Mapping, Work Flow 
ABSTRACT: 
This paper presents considerations and solutions, done by the National Survey and Cadastre (KMS), to overcome challenges in the 
transition from analogue to pure digital aerial image collection. Considerations and solutions are generalized - but are actually linked 
to the case, when production is executed through partnerships established by a EU-tender. 
1. INTRODUCTION 
In Denmark, aerial images are collected in March and April 
every year, before leafing, through a photo-campaign planned 
and organized by the National Survey and Cadastre (KMS). The 
purpose of the images are to revise the national topographic 
map database FOT (earlier TOPIODK), which is maintained in 
collaboration between KMS and the local municipalities in 
Denmark (FOT-Danmark, 2008 and Kort & Matrikelstyrelsen, 
2001). 
Images are collected through KMS, by one of a number of 
contractors found each year in an EU-tender-process. 
Each image collection campaign, are planned and organized by 
the chosen contractor, according to a set of detailed 
specifications defined by KMS in each years tender. Before the 
contractor is allowed to initiate the data-capture, the 
production-solutions must be approved by KMS. 
During the data capture and the following data processing done 
by the contractor, KMS are continuously involved in predefined 
quality assurance procedures and to secure the overall quality of 
the process and the final data material. 
2. EVOLUTION OF TECHNOLOGY 
Today the campaigns are fully digital. 
The transition from analogue to digital data capturing, has been 
prepared and implemented through a period of 4-6 years. This 
chapter presents an overview of the evolution of the data 
capturing techniques used for establishing and updating the 
national topographic map database (FOT / TOPIODK), and how 
these changes in techniques were adapted into the planning and 
production workflow. 
From the mid 90’s, when production of the Danish Topographic 
Map-database TOPIODK was first started, aerial images of one 
fifth of Denmark were produced every year, in scale 1:25.000 
using black/white film. After a period of about 5 years, when 
the databases were to be revised, the image media was changed 
from B/W to colour film. 
The analogue images were digitalized using photogrammetric 
scanners, and after that processed on digital photogrammetric 
workstations for further collection of 3D map objects. 
Around 2004 companies started to invest in digital aerial 
cameras. At that time there was great expectations but little 
knowledge, on how a transition from analogue to digital image 
data collection would influence the data workflow on 
specifications, data handling etc. 
KMS did at this time investigations concerning the digital 
technique and how it was adaptable into a traditional 
photogrammetric map update workflow (Brian Pilemann Olsen 
et al., 2005 and 2006). 
On this background, in 2005, KMS first extended its tender- 
material to allow contractors to offer the production done with 
digital cameras. For a start, digital production was an option not 
a demand. 
Through the image campaigns in both 2006, 2007 and 2008, 
parts of the productions have been done with digital captured 
images in GSD 10cm and 20cm. The image-scale was changed 
due to a shift in map-database-specification (FOT). After each 
production-year gained experiences have resulted in further 
revision of the tender material. 
3. EVALUATION OF TENDER 
This chapter gives an overview of the elements that KMS has 
changed in the tender-material around 2005, to do a first 
important step towards digital aerial image data collection. 
Elements are presented and discussed for their importance. 
As a consequence of investigations done in by KMS on the 
digital camera techniques, it was decided for a start, only to 
allow digital image production with digital cameras build on 
frame-technology. It is expected though that from 2009 the 
tender could be opened up for production with digital line 
scanners as well. 
3.1 Image extend