Map Comparitor Tool

Within the map comparitor is a pseudo-drawing tool with most of the normal drawing and construction element functionality.

When updating a cadastral unit, the map comparitor creates a new version of the cadastral unit using a Map Update (MU) application:

An MU application only exists within the DMS - the application is not recognised by the LRS.
An MU application number is based on the year created, the number generated within the current year, and the relevant cadastral unit number. For example
- 12ROX000012345 = application number for the first MU for cadastral unit ROX12345 created in 2012
- 12ROX100012345 = application number for the next MU for cadastral unit ROX12345 created in 2012.

Procedures for updating cadastral units or index entries affected by new OS map data

The following are the current practices used by MBM for updating cadastral units and index entries that are affected by new OS map data:

MBM will update all registered cadastral units and index entries where the external boundaries are affected by the new map data; this includes RAs, CDIs, TPOs, SPLs, etc.
If there is new map data that falls within a registered cadastral unit, no update will be undertaken.
If there is new map data that falls wholly within an RA, CDI or TPO, MBM will not update these index entries. The reason for this is that in the vast majority of instances, these index entries will only be viewed on the /wiki/spaces/2ARM/pages/64455340 when being searched & displayed whilst the plans officer is working on the registration of a cadastral unit. When viewed that way, the new map data is visible. It would only be when the index entry was viewed as a single entry (using the /wiki/spaces/2ARM/pages/63832205 option in the /wiki/spaces/2ARM/pages/62292068) that the new map data would not be visible.
When the changes to cadastral unit extents are minor or cosmetic, the decisions are made by checking the archive for extent deeds, etc. Please note, DMS casenotes are not longer updated by MBM.
If, after investigation, the discrepancies between the original legal extent of the cadastral unit and the new map data are too great to be resolved, the cadastral unit extent will be maintained.
When registered cadastral units are affected by new map data as a result of a P24 Check Survey, MBM will update all the affected cadastral units except those that abut/adjoin the subjects that the survey was instigated for. MBM will inform the plans settler of the cadastral unit numbers of the registrations that have not been updated. MBM will update those adjoining cadastral units under instruction from the plans settler as required.
When applications for registration that have been plans settled but have not yet been despatched are affected by new map data, MBM will not create an MU to update the cadastral unit. Instead, they will contact the plans settler who mapped the application and inform them that new map data affects the application. It is then the plans settler's responsibility to take the application back on and rework the mapping taking into account the new map data.
When registered cadastral units are affected by new map data as a result of a P98 request, MBM will update all the affected cadastral units ensuring that the new street name or number agrees with the property section of the title sheet.

Edge match or other poor-drawing problems on the DMS

If a plans officer encounters an example of an edge match problem, they should contact the MBM manager who will then investigate and resolve the discrepancy.

Example of an edge match

An edge match is caused when a new version of a map-tile is released onto the DMS, and that map-tile has updated map data that extends right to the edge of the tile. If the adjoining tile is not also updated and released onto the OS, the map data between the two tiles will no longer match up. Features on the map affected by an edge match will appear to be off-set or stepped in appearance, or in the case of a new feature or a removed feature, they will appear to be cut off.

Occasionally, examples of poor drawing by the OS or an error in the map will be found. Any such examples should be referred to the MBM Manager who will correspond with the OS with a view to resolving the problem. It is possible that, although the drawing is poor, it might fall within the OS published tolerances, particularly at 1:2500 scale mapping.

Example of poor mapping or error in the OS map

For example, a linear feature, such as a stream, that has been accidentally closed as a polygon with a straight line connecting the start & end points of the stream.

Another example could be when a curving feature on the ground has been generalised and captured by the OS as a straight line (or several straight lines). This may be acceptable within the published tolerances of the base scale of the map, or it may be that too much generalisation has been applied and the feature has not been correctly represented on the OS. In such an example, consideration should be given to the published tolerances before referring it to the MBM Manager.