Feedback on Scanning and

Orthophoto Generation

3rd June 2019

Workshop on Geoprocessing and

Archiving of Historical Aerial Images

Víctor J. García MoralesEngineer in Geodesy and Cartography

vgarcia@tracasa.es

Company Profile

Founded 1982

Expertise in Cadastre

Founding objective of assisting the Government of Navarra in the creation and

establishment of the Cadastre of Navarra

TRACASA Today Share Capital: 21,2 M€ Revenue 2018: 24,70 M€

Annual R&D Budget: 0,8 M€ Employees: 458

TRACASA is a government owned company, from the Navarra

Autonomous Region of Spain. Owned by the Government of Navarra

Government owned

Company

Business Units

GIS Solutions and

Cartography

Information System

Development and

Cadastre

Territorial Information Systems and Cartography (TIS)We work for government agencies and companies in the utilities industry developing tailored

solutions based on the specific needs of our clients, using Graphic information Systems Technology.

The SIT Business Unit complements its service offering developing Remote Sensing solutions working

with aerial sensor technologies for our clients in the environmental engineering industry and a full

range of Cartographic Production Services

Software Engineering and Information Systems and Cadastre (ISSI)We design, develop and deploy solutions working with Government Agencies, helping them deliver

improved and more efficient public services through the implementation and use of information

Technologies, we conduct Cadastral Surveying Projects and Land Management and Administration

projects in the Rural Sector

Navarra, just a step away from the world

Navarra Area: 10,391 km2 …maybe you know Navarra!

Where we belong…

An image is worth a thousand words

Historic aerial imagery offers an insight into the past.

Contents

Feedback on Scanning and Orthophoto Generation

- Aerial imagery Archive

- Scanning Methodology

- Ortophoto Production Methodology

- Applications

Archive of Navarra’s Government

1966 Navarra was in charge of its own cartographic

production, need for aerial imagery.

- More than 150.000 aerial images

- Negatives: cut or roll film

- Positive

- Color and B/W

- From 1927 – 2006

- Controlled: Temperature and humidity

Scanning the past - Archive

Scanning the past

Objective of the scanning:

- Preserve historical and irreplaceable information

>50 years, problem of conservation

- Priority: Older information and not proper conserved.

- Applications

- Orthophoto

- Web catalog

- Other products

Experience scanning

40% Archive is already scanned (Roll film and small part of the cut film)

Analog images scanned

- From 1996 till 2006: 60.000 Negatives scanned.

- After 2006: Historic areal imagery: 60.000 Negatives scanned.

Main scanning projects:

- 1927 – 1934: Navarra (10.000), Murcia (6.000), Álava (3.000)

- 1966 – 1967: Spanish National coverage: Navarra (2.000)

- 1987 – 1991: Navarra Cartographic production (7.000)

- 1992 – 1996: Navarra Upgrade cartography (7.000)

Scanning the past

Equipment:

Intergraph PhotoScan TD (1) 1996

Vexcel UltraScan 5000 (2) 1999/2000

Leica DSW600 (1) 2003 upgraded DSW700 v29 2018

Scanning the past - Scanner

Automate the scanning process:

Scanning the past - Scanner

Rebuild the roll film:

Vexcel UltraScan 5000

Any filmroll scanner

Scanning Methodology

1.- Analyse the analog images, to know the real status of

conservation.

2.- Create groups of images with similar characteristics,

belong to the same flightline.

3.- Pre-Scan at least one image to determine scan

parameters per group.

Scanning Methodology

4.- Cleaning: Removal of dust and other particles.

Scan room is clean and well ventilated.

Negatives are handled with lint-free gloves.

- Manually: If the negatives are cut

5.- Filmroll reconstruction (if it is possible)

- Automated: Roll film cleaning and neutralising electrostatics

6.- Scanning process: Set system parameters

Scanning Methodology

7.- Quality Control:

- Statistics 8/16 bits

- Direct Validation (saturation <5%,

wide dynamic range)

- Visual inspection: 1 or 2 per scan group

5-10% Project

New scan: Changing individual parameters. New pre-scan.

• Reducing the size of the patch window

• Deep clean

• Time exposure

• Change light parameter

MaxValue MinValue Mean Median Mode Standard Deviation Dinamic Range

4013 82 2016,07 1954 1135 824,37 3509

Scanning Methodology

8.- 16 to 8 bits conversion: Automatic process or define a

conversion for each group.

New QC 8bits images

9.- Database creation

- Flight metadata (Scan resolution, focal length, camera,…)

- Statistics

- Any comment related with the status

Scanning Methodology

10.- Georeferencing: Find an approximate location and

orientation for each image.

- Manually: One by one. Reference orthoimages. More

accurate – Slow / Individual images– Not always possible.

Dependency of other images from the same flight.

- Existing Flight plan: Georeference and use the photo shoot

mark to determine the centre of the image (XY)

- Relative orientation of group images: Measure minimum GCP

to georeference all the images. Low accuracy.

Scanning the past

Year A/DFlight

scale

Resolution

(microns)

GSD

(cm)

Scan

dateScanner

1927 - 1934 A 1/15.000 20 2005 Vexcel US 5000

1945 A 1/40.000 10 Unknown Digital images provided

1956 A 1/35.000 25 Unknown Digital images provided

1966 A 1/17.500 20 2009 Vexcel/DSW600

1982 A 1/20.000 15 2012 DSW600

1991 A 1/70.000 21 1996 Photoscan TD

1987-1991 A 1/20.000 15 2018 DSW600

1992-1996 A 1/20.000 15 2019 DSW700

1998 A 1/20.000 21 2000 Photoscan TD

2000 A 1/20.000 21 2000 Photoscan TD

2003 A 1/20.000 20 2003 Vexcel US 5000

2004 A 1/18.000 20 2004 DSW600

2006 A 1/18.000 13 2006 DSW600

2008 D 22

2009 D 22

2010 D 22

2011 D 22

2012 D 22

2013 D 22

2014 D 45

2017 D 22

2018 D 33

2019 D 33

Navarra whole Coverage:

Orthophoto Production

Navarra whole Coverage:

Year A/D Flight scaleResolution

(microns)

Ortho

(cm)Ortho date

1927 - 1934 A 1/15.000 20 25 2018

1945 A 1/40.000 10 45 2017

1956 A 1/35.000 25 100 2006

1966 A 1/17.500 20 40 2017

1982 A 1/20.000 15 30 2012

1991 A 1/70.000 21 187,5 1998

1987-1991 A 1/20.000 15 30 -

1992-1996 A 1/20.000 15 30 -

1998 A 1/20.000 21 42 2000

2000 A 1/20.000 21 42 2001

2003 A 1/20.000 20 40 2004

2004 A 1/18.000 20 40 2005

2006 A 1/18.000 13 25 2007

Wild C2

1927-1934: Methodology Orthophoto Production

Julio Ruiz de Alda

Military Pilot

Was born in Estella (Navarra)

During 1927 – 1934

https://wildstiften.ch/wp-content/uploads/2015/11/history_poster_pos_2010_en.pdf

- Total images: 10.000 (7.150 km2 aprox. 70% of Navarra)

- Purpose of the flight: Cadastre and Hydrology (River Basin)

- Camera used: Unknown. We assume Wild C2 (Focal length 165 mm)

- Original size: 10x15 cm (negative not available)

- Negative size: 20x30 cm (double size)

- Scanner: Vexcel UltraScan 5000. Manually scanned, 20 microns. 1 year 2007.

1927-1934: Methodology Orthophoto Production

Digital Images ATOrtho

RectificationMosaic

- Initial Exterior Orientation Parameters

- Approximate georeferencing:

- Location of each image was known approx.

- The Kappa angle was known approx.

- GSD: 10 - 20 cm.

AT Block per Cadastral Polygon (33 Polygons):

- Interior Orientation: No camera Information. Workflow = Digital Images

- Relative Orientation: Photogrammetric SW No able to obtain Tie Points

- Import Tie points from other SW: Extraction with Pastis – MicMac and other SW

- Absolute Orientation: No easy to find GCPs with accurate XYZ coordinates.

- Measured 50 GCPs per block.

- RMSE: 50 microns – 2.5 pixel – Less than 1 meter.

- New calculation adjacent block to reduce the number of AT blocks

1927-1934: Methodology Orthophoto Production

Digital Images ATOrtho

RectificationMosaic

- New block distribution to reduce differences.

- Digital Elevation Model for Orthorectification

- Creation of DTM stereo correlation.

- Gaps completed with existing Z information: Old contours lines,

existing DTM

- Orthorectification: 25cm pixel size.

1927-1934: Methodology Orthophoto Production

Digital Images ATOrtho

RectificationMosaic

- Before the creation of the final product: Improved the XY final accuracy.

- Image registration using the most accurate image: Churches, old buildings.

- Mosaic the orthorectified images, radiometric balance.

1927-1934: Methodology Orthophoto Production

Digital Images ATOrtho

RectificationMosaic

- SDI Website

- FTP download Orthoimages

- Individual aerial images

- Web Catalog

1927-1934: Methodology Orthophoto Production

https://cartotecayfototeca.navarra.es/cartoteca/

https://idena.navarra.es/navegar/

Applications

- Define boundaries

- Cadastre/Urbanism: exact definition when a building was built

- Ancient Cattle Roads

- Hydrography:

- Changes of the river bed

- Creation of DEM (Reservoirs)

- Multitemporal analysis:

- Quarries

- Evolution Urban Areas

- Land Use

The need of scan historical archive: Bad conservation,

looses of irreplaceable information.

Scanning process:

10% Scan – 90% rest

Reduce number of Photogrammetric Scanner

Importance of Georeferencing and AT to create

measurable products to perform analyses

Final remarks

Feedback on Scanning and

Orthophoto Generation

Víctor J. García MoralesEngineer in Geodesy and Cartography

vgarcia@tracasa.es

Any question?