iv. Improvements in data 
compatibility. 
Although no radical new theories or 
methodology emerged it was 
particularly evident that the process 
generally could be greatly simplified 
and speeded up given a properly 
facilitated approach. 
THE WAY FORWARD 
The continuing expansion of 
geographic information systems (GIS) 
has ensured that these general 
principles remain very relevant and 
while things have moved on somewhat 
since this report was compiled they 
still. form ‘the -basis' for further, 
properly resourced research and 
development. 
Within Ordnance Survey of Northern 
Ireland (OSNI) action to improve the 
updating operation by partly building 
on these recommendations, has 
continued and it is presumed that 
others have made similar efforts. 
Thinking here has also increasingly 
focused on how the full potential of 
aerial photography could be exploited 
to enhance the process. 
PROGRESS WITHIN ORDNANCE SURVEY OF 
NORTHERN IRELAND 
Within  OSNI considerable advances 
have since been made with respect to 
each of the recommendations, progress 
here being largely dictated by the 
demands for up to date information in 
support of the Northern Ireland 
Geographic Information System 
(NIGIS). With the OSNI large-scales 
digital topographic database the key 
locational element of this 
continually developing multi-partner 
network it is imperative that this 
database can meet the requirements of 
a very diverse range of application 
areas, with equally diverse demands 
for content and currency. While 
there is still much to be done to 
produce an ideal updating flowline, 
enhancements which have recently been 
implemented have resulted in a 
34 
significant increase in throughput, a 
very satisfactory development given 
the complexity of the data and 
consequently of the actions necessary 
to update them. 
The main developments in respect of 
each of the recommendations in the 
earlier report have been as follows. 
Recording the Time/Historical 
Dimension 
OSNI has developed and implemented a 
new methodology which provides for 
both current and historic archiving 
of graphic and textual data, and in 
addition allows for the provision of 
change only data from the large scale 
database. The historic archive is 
created by marking each linestring, 
point and object feature within the 
graphic file with a date of survey 
and a date of deletion where 
appropriate. A date of revision is 
also given to features which have 
been altered but which are related to 
unchanged geometry. The date 
attributes are held within the 
graphic file and enable OSNI to 
extract deleted geometry and store 
this as a discrete layer within the 
database structure. The date of 
survey 1s taken as the date the plan 
was first digitised while the dates 
of deletion and revision are taken as 
the date at which the graphic file is 
updated by the digital updating 
section. There 1s currently a 
turnaround time of five working days 
between the date of survey of the 
deletion/revision and the date of 
digital update and additional 
resources will be applied to the 
updating process to further reduce 
this time delay. 
Production of User Friendly/Cost 
Effective Updating Procedures 
The move to the new updating 
procedures together with advances in 
software have allowed OSNI to develop 
a much more intuitive user interface 
for the updating process. The 
software now utilises drop down menus 
with 'mouse' selection to facilitate 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996 
=r OH PD CEO