OTISS allows users to load in their own estate, site maps, topo plans, CAD drawings, etc. OTISS can deal with a range of different map and plan formats.
If you don’t have a site map, you can still use the ‘online’ maps provided with OTISS. These include Google Aerial and Google Streetmap. But we also provide OpenStreetMap which is better than Google Streetmap because it has much more detail about woods, hedges, footpaths, buildings, fences, streams, etc. You can only zoom in so far with these online maps, whereas you can zoom it closer with your uploaded maps.
In OTISS we use the terms site plan and map – but they are basically the same thing. A more important distinction is whether we have enough geo-reference/GPS/location information to locate the map/plan in the ‘real’ world. Site plans without this geo-referencing information cannot be used with GPS nor can the site’s trees/furniture be used with the ‘real’ world maps such as Ordnance Survey, Google, OpenStreetMap, aerial maps, etc.
Buying Ordnance Survey maps for OTISS
Please read the following sections to see what type of map is suitable for your requirements.
OS MasterMap (CAD DWG/DXF): Suitable for housing developments and small sites – covering an areas of 100m x 100m and larger. OS MasterMap can get quite expensive as the area increases. For areas above 500m x 500m, you could consider getting several smaller maps or using a 10K scale map (see below). Select DWG or DXF depending on your own requirements – OTISS will accept both formats.
OS MasterMap (Raster): Suitable for housing developments and small sites – covering an areas of 100m x 100m and larger. OS MasterMap can get quite expensive as the area increases. For areas above 500m x 500m, you could consider getting several smaller maps or using a 10K scale map (see below). Always request a “Georeferenced TIFF” format file – not just “TIFF”. You should also receive a corresponding World File (.tfw) that contains the geo-referencing data. You will need to load both files into OTISS.
OS MasterMap PDF/TIFF/JPG: Suitable for housing developments and small sites – covering an areas of 100m x 100m and larger. The PDFs are usually sold as A4/A3 sizes and must have a scale (1:200, 1:500, 1:1250, etc). Once uploaded, these site plans can be used with OTISS and the mobile survey app. But these file formats do not contain any geo-reference/GPS/location information, therefore they cannot be used with GPS nor can the site’s trees/furniture be used with the ‘real’ world maps such as Ordnance Survey, Google, OpenStreetMap, aerial maps, etc. However, these files (usually) have clearly marked reference points. After you load them into OTISS, you can manually add the geo-reference information – see below for full instructions. If you have a choice always request, either the CAD or “Georeferenced TIFF” formats described above.
OS VectorMap 1:10,000 (CAD DWG/DXF): Suitable for estate-wide maps covering an areas of 1km x 1Km and larger. Select DWG or DXF depending on your own requirements – OTISS will accept both formats.
OS VectorMap 1:10,000 (Raster): Suitable for estate-wide maps covering an areas of 1km x 1Km and larger. Always request a “Georeferenced TIFF” format file – not just “TIFF”. You should also receive a corresponding World File (.tfw) that contains the geo-referencing data. You will need to load both files into OTISS.
Note: the different map vendors may use a variety of product names for the OS maps, e.g. Block Plan, Land Plan, Location Plan, Planning Map etc. The file formats are what is important for OTISS.
PDF and Image files
A site plan has been supplied to you as a PDF, image or photo file. The file can be in .PDF, .TIF, .JPG or .PNG format. These files will be uploaded onto the OTISS server where they are stored on our OTISS map server. They can then be presented on your browser or mobile survey device as a base map for your survey.
When you load a PDF into OTISS, you will also need to enter a scale (1:200, 1:500, 1:1250, etc). For other images, you need to specify how many pixels represent a metre length. Who-ever provided you the image should tell you the scale factor in terms of “N pixels = M metres”. For accurate surveying and placement, the image cannot be used without this information.
Once uploaded, these site plans can be used immediately with OTISS and the mobile survey apps.
But these file formats do not contain enough geo-reference/GPS/location information, therefore they cannot be used with GPS, nor can the site’s trees/furniture be used with the ‘real’ world maps such as Ordnance Survey, Google, OpenStreetMap, aerial maps, etc. However, if the image contains clearly marked points with known GPS coordinates (eastings/northings, longitude/latitude), then you can overcome these drawbacks by first loading the PDF (as shown here), and then ‘geo-referencing’ the image (see below for full instructions).
CAD – DXF and DWG files
OTISS allows you directly import CAD drawings and create site maps. OTISS will convert the drawing into a GIS image and store it on our map server. The drawing can then be used like any other uploaded map or site plan – you can pan/zoom around the map and plot trees and furniture onto the drawing.
Along with the CAD file, you will be asked to specify Drawing unit (usually metre or millimetre) and the Map co-ordinates to use (typically “UK Ordnance Survey” or just “Plan x/y”). Whoever provided you the drawing should be able to tell you this information.
Important: When you get drawings from an architects office, they have often: rotated the drawing to make it print better; added legend boxes; added detailed insets; include lots of unnecessary layers and details; include objects extra situated alway from the main site. Such drawings are absolutely no use for surveying or for use with GPS – especially if the site was rotated.
Ask your architects for a simple, uncluttered DWG of the original site, with a drawing unit of 1m or 1mm, with North at the top, with co-ordinates based on the grid reference and with all unnecessary objects/blocks/AECs hidden or deleted.
There are some restrictions on what CAD drawings can be loaded in this way.
- Only DWG and DXF formats are supported. DWG file formats AutoCAD2013 and earlier.
- OTISS can only load drawings where the ‘Drawing unit’ is either 1 metre or 1 milli-metre.
- For drawings that cover an area over 1km wide, the resolution of the GIS image created from the CAD drawing may start to deteriorate. The map co-ordinates will still be accurate and the image suitable for surveying, but better resolution could be achieved by splitting the CAD drawing into smaller sections and loading them as separate sites.
- For drawings that cover an area over 5km wide, the accuracy of the map co-ordinates may deteriorate. If the drawing cannot be spilt into several smaller sites, then its best to check the accuracy of the map co-ordinates and adjust as required. See the section of Geo-referencing below or contact the OTISS support team.
- Overly complex or very large (> 7Km) drawings are not supported. Try to spilt it into several smaller, simpler drawings or contact the OTISS support team – we may be able to help out.
Trouble loading CAD drawings
(1) Sometimes OTISS says that the drawing area is too large, but you know its not! Often the drawing contains extra objects that are not near the main site you are interested in, but they make the drawing cover a much larger area – its a common problem!
Open the drawing in your CAD application and try these alternatives to locate the extraneous objects and then delete them.
- (a) Use ‘Select All’ then ‘Zoom to Selection’, You may see the main area of selected objects, and also lots of others that are away from the main area. Select and delete the extraneous objects.
- (b) The ‘Zoom to Extents’ command appears to shows a blank drawing – but it actually shows co-ordinates 0,0 and a tiny spec where the topo site is. There may be a few objects located at coordinates 0,0. Use a Rectangle to select and delete these. Then try ‘Zoom to Extents’ again.
- (c) The ‘Zoom to Extents’ command shows that the drawing covers a much larger area than just the site you are interested in. Select and delete the extraneous objects.
- (d) Use a Rectangle to select all items on the main area of interest, then Invert the selection and delete these selected (extraneous) objects.
Once the extraneous objects have been deleted, the ‘Zoom to Extents’ command should zoom in to show the main area of interest. Save the drawing file and try again to load it into OTISS.
(2) For those CAD drawings that cannot be loaded directly into OTISS, there is an alternative. They need to be converted to a PDF or JPEG/PNG image. Your architect can normally do this for you. Alternatively you can use the free tools available on the web – e.g. Autodesk® DWG TrueView™ software. For a site area of a few 100metres, an image file of 2000×2000 pixels is sufficiently clear for using as a base map. Then, if the image contains clearly marked points with known geographic coordinates (e.g. Ordnance Survey grid reference points), then you can ‘geo-reference’ the image – see below.
Map Images and World files (Georeferenced TIFF)
This is the case where your map has been supplied to you with a corresponding ‘world file’ that contains geo-spatial information. These maps can be overlaid on top of other maps such as Ordnance Survey, Google OpenStreetMap, etc.
The image file can be in .TIF, .JPG or .PNG format, and the world file must have a corresponding file extension of .TFW, .JGW or .PGW respectively.
Who-ever provided you the map should tell you the Map co-ordinates or Map projection to use – typically this is the national grid.
Geo-referencing your site plans
OTISS allows you to add/adjust the geo-reference/GPS/location information for a PDF or aerial image so that the map can be accurately positioned in the ‘real’ world. This allows you to use the GPS location features on the mobile survey apps and to overlay the site’s trees/furniture on top of base maps such as Ordnance Survey, Google, OpenStreetMap, aerial maps, etc.
IMPORTANT: The map must already have North at the top of the page. This tool cannot be used rotate a map. You will need to get a better map.
VERY IMPORTANT: You must do all geo-referencing before starting any surveys – otherwise the tree/furniture positions will be wrong – and it is difficult to correct later.
IMPORTANT: For CAD drawings, we strongly recommend that you use the CAD application to move/re-position the drawing so that the X/Y co-ordinates match the easting/northing values – this approach is much more accurate. Then load the fully geo-referenced drawing into OTISS.
Firstly, create the site and load in the PDF site plan (as described above). Secondly goto the Manage Maps & Plans page, select the map/plan and press the Geo-reference button. The Geo-reference page requires you to select two known points on the site plan and to provide accurate GPS co-ordinates (easting/northing).
- Select the Map co-ordinates to use for this map – typcially this is the national grid.
- Zoom in (as much as possible) to a known location on the map. Press the Add button and place/drag a marker to the location. Once you have placed the marker, you can zoom out again to read the map better. In the side panel, enter the exact map co-ordinates for this point. Note: the most common error is entering the East/X/Longitude and Northing/Y/Latitude values in the wrong boxes.
- Repeat for a second point. For most accurate results, the two points should be on diagonally opposite corners of the map.
- Press the Apply button and the map will refresh with the updated co-ordinates.
- Zoom around the map to several places and check the accuracy of the new co-ordinates by comparing the mouse positions shown in the side panel against the known positions on the map.
- If required, repeat the process to improve the accuracy.
- Use the Restore button if you need to start again, or go back to the Manage Map & Plans page and upload the map again.
Survey sites – with Maps and Plans
Within OTISS, an estate is divided into ‘sites’. Each site can be linked to a user supplied map or plan, or can simply use the online world maps.
- When a site is linked to a geo-referenced map, then it (and its surveyed items) can be viewed on the map which is overlaid on top of the world map. The map page allows you to easily show or hide each layer as required.
- When a site is linked to a non geo-referenced plan, then it (and its surveyed items) can ONLY be viewed on the plan, and not on the real-world maps
Maps and licensing
You don’t need any special or extra permission to place your maps on OTISS – nothing extra beyond the normal permissions or license that you already need to use the map.
When you load a map or plan onto OTISS; it is only accessible by you (and other OTISS users that you authorise), it cannot be viewed by the general public or other OTISS users. As such, loading the map into OTISS will normally be permitted by the person or organisation who supplied the map. If you have any doubts, then please check with your suppliers.