Here is a list of some know bugs you may come across. Our aim is to keep this list very small!

PDFs don’t open automatically in Chrome

The Autumn 2019 releases of Chrome have a bug where they don’t open PDF files correctly – all you get is a grey screen. This affects all websites that provide PDF documents. We see this in OTISS when we generate PDF reports – but only see a grey screen (annoying!).

The Chrome support website provides a set of instructions to get around this issue by ‘downloading’ the PDF file rather than displaying it – see here.

Hopefully they will fix this soon and release a new version of Chrome.

Site/Topo plan does not align exactly…

When you load in a site plan, topo or CAD drawing, you can overlay it on top of Google Road/Aerial and OpenStreetMap. But sometimes the roads or buildings don’t seem to align 100% in all places. Why is this?

Differences between maps is a constant and recurring issue we have to live with. The Google Maps are based on a spherical view of the earth, whereas the UK O.S. is based on a flattened representation of Britain. There is always some differences and some distortion. E.g. a square section of an O.S. map looks distorted when overlaid on a spherical Google Map.

Secondly, if you compare your topo, with the Google Road, Google Aerial and OpenStreetMap you will see that they are all slightly different. Remember that Google road map is not even trying to show a per metre accurate layout for roads – it’s purpose is for Sat nav, deliveries, advertising, and selling stuff. The Google Aerial images are taken from planes; items directly below the planes are ok, but others can appear to be offset a little depending on the angle from the plane to the tree/building. The Ordnance Survey maps will tend to be much more accurate than the others.

When you have several maps from different sources, you have to choose one of them as your main map, and use the others merely as an extra reference or guidance.

Photos in survey apps – cannot take a new photo…

The Android system has an inbuilt set of security permissions and a strict rules for controlling them (read more about permissions). The OTISS survey apps follow the Android guidelines and will ask your permission to allow the app to use the camera – typically you only have to do this once.

Normally this works fine, but occasionally the Android system seems to withdraw the permission or never gets around to asking you. In this case the Camera icon is disabled and the app cannot use the camera until you do the following.

  1. On your phone/tablet, open the main Settings app
  2. Tap Apps or Application Manager (depending on your device, this may look different).
  3. Tap the app you want to update.
  4. Tap Permissions.
  5. Next to a permission you want to turn on, move the switch to the right until it turns green. If you want to turn a permission off, move the switch to the left until it turns gray.

Bug in survey apps – Survey Form does not always appear…

This issue is seen very rarely, and is only an issue on some manufacturers phones/tablets and only when running certain releases of the Android software. It usually stops happening when the manufacturer releases a software upgrade.


When using the maps to survey a site and you try to Add or Edit a tree/item, the survey form should appear. But on some devices the survey form does not always appear, the map disappears and you are returned to the list of surveys. Trying the same action again often does work for a few times, but then it fails again – it is all a bit random!

This behaviour is due to a bug in a combination of the Android operating software and the device’s hardware.

The fix:

  • Go to the Survey App’s Main Menu.
  • Click on the Settings icon at the top of the page.
  • Scroll down and find the setting for “Enable hardware acceleration for map“.
  • Untick this feature and press the back button.
  • All done!
  • Start surveying again and everything should work correctly. There may be a ‘very’ small slowness when you pan and zoom around the maps, but it is not very noticable.

If you are still seeing the problem after disabling the hardware acceleration above, then please contact our support staff.

Bug in survey apps – Download Offline Maps…

This issue is only seen in older Android 4.x devices and in low-spec/cheap tablets.


While downloading a large set of map tiles, the app just stops doing the download and returns to the Downloaded Surveys menu. Whereas, it should complete the download and display a message beneath the map to say the download is complete.

This behaviour is due low memeory or low performance of the older Android operating software – we think!

The fix:

When requesting a download, simply zoom in a step further and download the required area in several smaller areas.