Landwrap September 2009 - e-survey

Improving spatial accuracy in Landonline

LINZ has undertaken several streams of activity to improve the spatial accuracy in Landonline to assist surveyors working in non Survey-accurate Digital Cadastre (SDC) areas.

Data re-adjustment pilot

A recent pilot project included connecting to additional geodetic control to improve spatial accuracy. This was undertaken in the Far North, Piha in West Auckland, and the Wairarapa.

Discrepancies ranged from being good at +/- 1m to bad at +/-10 to 15m. After the geodetic adjustment pilot, the overall accuracy had been improved to +/- 2m.

As a result of the pilot work, surveyors are already seeing the benefits.

LINZ will continue to investigate the most effective way to apply the technical solution to upgrade the cadastre throughout New Zealand to +/-1 to 2m.

More information on activities to improve spatial accuracy and the data re-adjustment pilot is available in the February edition of Landwrap.

Using the exception process

The key activity was an enhancement in Release 3.1 that allows the exception process to be accessed at any stage during capture by e-survey users.

Analysis of the exception process showed that surveyors gained efficiencies if they used the process as soon as problems are identified, i.e early in the capture.

This enhancement also allows anyone working on the survey to enter the exception process, not just the submitting surveyor.

A checklist and information on the exception process are available on this website:

• Exception process for e-survey
• When to raise an exception request
• e-survey Tip & Hint – Exception requests

Clearing the backlog of cadastral network adjustments

LINZ is continuing to improve the network adjustment process, and keeping the level of adjustments waiting to be completed to a minimum. Extra staff have been trained in the process to ensure a backlog does not build up. This work allows surveys to be quickly integrated into the cadastre and underlying issues addressed much faster.

Submitting two datasets

When encountering problems in non SDC areas, some surveyors lodge two datasets. The first survey is a control survey or redefinition to enable the cadastre to be adjusted prior to completing the subdivision. However, when following this practice, the surveyor needs to indicate in the survey report of the control survey that an adjustment is required to better align the cadastre, and request LINZ to let them know when the adjustment has been completed.

Improvement to Hawkes Bay control data

As part of the geodetic work programme, 6,500 geodetic marks have been assigned improved coordinates in the Hawkes Bay. For information on this work, see the April edition of Landwrap.

New e-survey tips and hints

The e-survey Tips and Hints on the Landonline website are continually being refined and added to.

Mark purpose

The following are tips for choosing mark purpose in Landonline:

• Any mark that forms part of a boundary on any parcel (including non primary parcels) in Landonline should have a purpose of boundary. The reason for this is that boundary marks can only obtain a best possible order of 7th where traverse marks can be 6th order or better. So if a boundary mark is incorrectly set to traverse then it can get an incorrect order.
  
  
• All adopted marks other than boundary marks must be set as a purpose of traverse, as Landonline will not accept adopted witness or origin marks. Any adopted marks set to Witness or Origin will fail pre-validation.

Linking multiple parcels

When linking a large number of parcels, Landonline redraws all layers turned on each time you link.

To speed this up, you can do the following:

1. Turn off all layers except Survey Capture, see screen shot 1.
   
   

   Screen shot 1

2. Turn off all layers except CSC Parcels, see screen shot 2.
   
   

   Screen shot 2

   This will speed up the redraw when linking parcels and significantly reduce parcel linking times for plans with large numbers of parcels, see screen shot 3.
   

   Screen shot 3

3. To make this process even easier you can tile your parcel capture and spatial windows to avoid having to go back to the parcel capture window each time, see screen shot 4.
   
   

   Screen shot 4

Are you using the e-survey best practice tools and tips?

Spanning a wide range of topics, the best practice section includes the tips and hints full index.

The e-survey training resources section has all the links and background on training materials provided by LINZ such as the user guide, computer based training (CBT) DVD, and the support available to surveyors.