Georeferencer - Frequently Asked Questions

How do I generate an image of a pdf plan to use in the georeferencer tool?

There are a few methods that can be used to convert a PDF plan, or part of the PDF plan into one of the acceptable image formats (jpeg, jpg, png, or tiff) to upload into the georeference tool. Method 1 is the simplest and most straightforward, but officers can decide which one to use depending on the nature of the plan and what needs georeferenced.

 Method 1

1. Zoom into the part of the plan to be georeferenced, ensuring that there is sufficient surrounding map detail to generate the appropriate number of control points for georeferencing.

2. Open the Snipping Tool.

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3. Select + New and drag around the desired area of map.

4. Save the Snip to the desired file location. The default setting is JPEG but the snip could also be saved as a PNG file.

5. Upload the image file to the georeferencer tool.

Method 2

1. Download the PDF plan, or if the plan is part of a deed you can use Print to PDF function to save the page that is the plan, to the desired file location.

2. Open Microsoft Copilot, M365.

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3. Press the + button to upload the PDF to Copilot.

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4. Type in “Save this PDF as JPG*/TIFF*/PNG* file (delete * as appropriate).

5. The image will be generated. Select the Download button to save the image to the desired file location.

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6. Upload the image file to the georeferencer tool.

If using Copilot, so long as it is accessed via M365 as described above then all content is protected by the RoS Enterprise Data Protection rules with the same security as any other file on a users laptop.  This means that anything uploaded is private to the officer who uploaded it, and no data is used to train the model or in any way shared between colleagues or outside of RoS.

 Please note that use of Copilot should be in line with RoS published AI policy.

Method 3

1. Download the PDF plan, or if the plan is part of a deed you can use Print to PDF function to save the page that is the plan, to the desired file location.

2. Open the PDF plan with ABBYY FineReader PDF.

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3. Save the PDF using the “Save Pages as Images” option to the desired file location. The default save format is TIFF,Colour,JPEG Compression (*.tif, *.tiff). The file could also be saved as either a JPEG or PNG file.

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4. Upload the image file to the georeferencer tool.

Please note that depending on the map size and scale of the PDF plan, some TIFF files may be too large to import into Plan Creator, especially if the Unpacked TIFF option is selected. If the subjects on the deed plan are relatively small compared to the overall plan size, or a user only needs to georeference part of the deed plan, then Method 1 may be the better option and should suffice in most scenarios.

How do I know which transformation I should use?

The detailed guidance for the transformation types available in Plan Creator and which to use is in the guidance page on What is georeferencing?

If I need to use a Warp transformation but cannot find 8 reliable GCP's required to perform the transformation, what should I do?

Assuming the Affine transformation is not suitable or does not produce acceptable results, please refer up to your business lead in the first instance who would be able to advise on next steps.

The subjects I have to plot are large with a lot of the boundaries not being defined on the OS Map and I cannot get the transformations to produce acceptable results. What should I do?

If the subjects are on a new plan based on the OS Mastermap, then obtaining the digital data should be the first option in this scenario.

My georeferenced image is sitting slightly off the latest OS map, and if I could shift the image it would overlay exactly with the OS Map. Can this be done?

Freehand movement of the georeferenced image would destroy the spatial relationship between the chosen control points. Ensure that control points are chosen to surround the subjects to be georeferenced, and either add more control points or delete existing ones depending on the RMS error of the existing points, or a different transformation type.

I have georeferenced the plan but the overlayed image it is still not sufficient for plotting, and I have located control points surrounding the subjects as advised. What do I do?

It could be that the plan is just not sufficient quality for georeferencing for various reasons such as it has been stretched or folded etc. If it cannot be plotted and scaled from, and is required for an ownership reference, consider rejection and referral to HEO. If the plan is for other reference, follow the guidance in the manual for Plans References for Servitudes, Burdens and Non-Ownership Rights.

Can plans officers’ georeference from prior versions of the OS map (meaning MasterMap) associated with previous authorised / approved versions of registered titles?

It is not possible to georeference directly on a prior version of the OS map; however a snip of the map can be taken that includes sufficient surrounding detail to use as control points and that can be georeferenced in relation to the latest OS Map.

I have a deed plan based on the county series map, but the map does not exactly overlay with the latest OS map and the features are offset. Can I still georeference from this plan?

The overlay of county series map in PC/PV will never sit exactly on top of the latest map due to improvements in surveying techniques, and in 1:2500 areas, positional accuracy improvement.

However, provided that the deed plan has a sufficient number of features to allow the requisite number and location of control points to be identified for georeferencing, a snip of the county series map can be taken that includes sufficient surrounding detail to use as control points and that can be georeferenced in relation to the latest OS Map. The deed plan can then be georeferenced using the georeferenced county series overlay. However, this extra step may not be required if you can easily identify the feature on the County Series version is also available on the current version of the basemap.