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Positional accuracy improvement programme

FAQs and comments

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December 2002

General

How does PAI affect my organisation?

In discussions on PAI, I have heard there are different measures of accuracy. Please explain.

Apart from a different absolute accuracy level what other differences are there between the PAI of rural towns and the PAI of other rural areas?

What time and resource will we need to cope with moving our data to the new map positions?

How is data matched at the external edges to positional accuracy improved blocks?

Only 1:2500 scale data is being addressed under PAI but what happens to those tiles which have a mix of scales (Dual Accuracy)?

OS MasterMap®

Is the PAI programme going to improve OS MasterMap data in preference to Land-Line® map tiles?

Should I wait until the PAI is finished before migrating from Land-Line to OS MasterMap?

How will link files apply to OS MasterMap, which is not tile based?

How will I identify the improved maps and features in OS MasterMap?

How can I keep the non-PAI areas of OS MasterMap up-to-date without including PAI data into my holding while I make the necessary shifts?

I want to obtain a version of OS MasterMap just before my area is PAI’d. When do I need to order to ensure this occurs?

Land-Line®

I have loaded a 1:2500 scale map tile where part of one edge does not match the data on the edge of the adjacent tile. Why is this?

How will I identify the improved maps and features in Land-Line?

Link files

By inspecting a map and its link file, it showed that some features have moved to a different position but others haven't. Isn't all map data positional accuracy improved?

Will the link file format in .csv be static?

Will the number of points in the .csv file vary depending on density?

Are the number of points in the link file random?

Why doesn’t Ordnance Survey provide or, at the very least, recommend a transformation system for use by its customers?

What is the best way to process data – one pass per data layer using all tiles or one pass per tile for each layer?

If organisation A uses product 1 and organisation B product 2, there’s a risk of the same data being transformed differently. Shouldn't there be only 1 solution for all of the UK?

I understand transforms on data that matches to OS MasterMap/Land-Line detail, but how do we accurately move data with no association?

Impact on other products

Will OSCAR® be affected by the PAI programme?

Will ADDRESS-POINT® be affected by the PAI programme?

Will Landplan® be affected by the PAI programme?

Will Boundary-Line be affected by the PAI programme?

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