Manawatu Whanganui 0.3m Rural Aerial Photos Index Tiles (2015-2016)

Manawatu Whanganui 0.3m Rural Aerial Photos Index Tiles (2015-16)

Toitū Te Whenua Land Information New Zealand

2016

Index Tiles ONLY, for actual orthophotos see layer [Manawatu Whanganui 0.3m Rural Aerial Photos (2015-16)](http://data.linz.govt.nz/layer/88146)

Orthophotography in the Manawatu-Whanganui Region Region taken in the flying season (summer period) 2015 -16. Coverage is in the Ruapehu, Wanganui, Rangitikei,
Manawatu, Horowhenua and Tararua Districts.

Imagery was captured for the ‘MW LASS’ by Aerial Surveys Ltd, Unit A1, 8 Saturn Place, Albany,0632, New Zealand.

Data comprises:
•2,015 ortho-rectified RGB GeoTIFF images in NZTM projection, tiled into the LINZ Standard 1:5,000 tile layout
•Tile layout in NZTM projection containing relevant information.

The supplied imagery is in terms of New Zealand Transverse Mercator (NZTM) map projection. The products are tiled into NZTopo50 1:5,000 tiles. Please refer to the supplied tile layout shape file for specific details, naming conventions, etc.

Imagery supplied as 30cm pixel resolution (0.3m GSD), 3-band (RGB) uncompressed GeoTIFF. The final spatial accuracy is ±0.6 m @ 68% confidence level in clear open spaces.

Data Acquisition:
The aerial photography for this project was captured within the 2015/16 flying season (September
2015 – April 2016) on the following dates:
19 November 2015
28 December 2015
6 January 2016
13 January 2016
23 January 2016
12-13 February 2016
2 March 2016
9 March 2016
13 March 2016
22 March 2016
31 March 2016
14-15 April 2016
21 April 2016
11 September 2016

All photography was captured using Vexcel's digital UltraCam Eagle and UltraCamLp cameras and
flown at:
0.3 m GSD: 18,928 ft (5,769 m) flying height
0.3 m GSD: 11,486 ft (3,500 m) flying height
Camera Lens: 100 mm (UCE) and 70 mm (UCLp)

Sun Angle
Minimum of +35 degrees

Data Processing
All aspects of the data processing from imagery processing to DTM creation and ortho production
and product deliverables was undertaken in-house by Aerial Surveys staff.

Map Projection
All spatial data for this project provided in terms of New Zealand Transverse Mercator 2000 map
projection (NZTM2000). The datum is New Zealand Geodetic Datum 2000 (NZGD2000). The height
datum is orthometric Moturiki 1953 (sea level).

Image Processing and Aerial Triangulation
All imagery has gone through QA checks ensuring there is no cloud cover and cloud shadow. During
aerial acquisition the aircraft on-board GPS navigation data and ground base station data collected
and post processed. Imagery processed to level 3 and checked for colour correctness/radiometry and
even tonal balance across each project area. The aerial triangulation brings together the GPS data
and imagery using a two part process which stitches the imagery together using tie point matching
for the relative orientation phase and observing ground control points for the absolute orientation
phase. LINZ control, 8th order horizontal and 4th order vertical and other existing control from Aerial
Surveys control data base were used to strengthen the block adjustment or as independent checks on
position during final QA of the ortho imagery. A final report is generated to check RMSE values are
within specification.

DTM Creation
The DTM creation was collected from stereo imagery using photogrammetric techniques, largely
automated pixel matching and auto-correlation process that creates mass points of the terrain surface
with extensive further manual editing to remove points on water bodies and extensive breaklines
added around water bodies and along all ridges, valleys and areas of steep terrain change, such as
kerbs, retaining walls, drains. In areas of dense vegetation form lines are collected. The final DTM
took the form of breaklines and mass points. A Triangulated Irregular Network (TIN) was then created
and used for the ortho rectification process.
DTM Accuracy: ±0.6 m @ 68% confidence level in clear open areas (1 sigma)

RGBI Ortho Rectification Process
Ortho rectification is the process of removing (from the image) the effects of camera tip/tilt and
displacement caused by terrain relief. During this process each frame is 'draped' over the terrain
model and the photograph then becomes 'scaled' and 'levelled' in terms of true ground coordinates.
The generation of seamlines between frames follow natural physical features such as ridges, valleys,
roads and rivers. The seamlines are used for the final ortho mosaic that stitches the imagery together
using feather mosaicking techniques. The ortho imagery is then extracted aligned to LINZ 1:5000
sheet tile layout.

-40.8034350538 174.936918847 -39.0347055222 176.653368623

https://data.linz.govt.nz/layer/88096-manawatu-whanganui-03m-rural-aerial-photos-index-tiles-2015-2016/

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