PhotoMap Quirks
The PhotoMaps are automatically generated after each flight so there is no human inspection of the PhotoMaps. To check each image after each flight would take a very long time as there are over 100,000 photographs taken for an average city survey area. Instead we get them to you as soon as they are available but the consequence of our fast turnaround is that there may be visual errors in the data from technical implications and/or cloud etc which we haven’t edited out.
Q&A
Q. Why do some survey areas appear cut short or incomplete?
A. We aim to fly when the weather is at its best and when we have obtained an Air Traffic Control (ATC) clearance. However, sometimes we might start a flight in the best conditions but not be able to finish the flight because these conditions have changed. For example, we might obtain a clearance from ATC to fly a certain area but then they might change their mind because there is heavy traffic and they can't let us continue. In this case, we will have to abort the flight. Alternatively, unexpected cloud might start to creep in mid-flight. In this case we will make the executive decision whether to abort or continue based on how much of the survey is left and how heavy the cloud cover is.
If we do have to abort a flight, we will make it a high priority to fly the area again at the earliest time possible, when the conditions are in our favour.
Q. There is an obvious edge in the PhotoMap I am looking at. Can this be removed or blended?
A. Sometimes we may show overlapping surveys and at some places, this may affect the edges of the survey. We may fly different surveys at different resolutions and scales. For example we may fly a very high resolution for a smaller area. If this is the case, you will have surveys of different dates shown overlapping each other.
Q. Why is there a white sheen over an area of water I am looking at?
A. You may see a glint or glare over an area of water. Zooming in on the PhotoMap can remove this as the camera settings used to capture close detail are different to the settings we use for the other cameras.
Q. Why is there a dark ‘smudge’ in a light area?
When extremely dark and light areas are captured, our system automatically adjusts and matches the colour intensity to provide you with PhotoMaps which show the best detail. Some of the older PhotoMaps are very dark because we flew those surveys at near darkness for test purposes.
Q. Why is there is a light coloured haze covering some of the PhotoMaps?
A. If you come across a light grey or white section in our PhotoMaps it is safe to say that it is a little section of low-lying cloud. We try to fly in only the best weather conditions however a minute amount of low-lying cloud is inevitable and we apologise for any hidden PhotoMap detail. These too will then unfortunately create a shadow (dark blue smudge) across our PhotoMaps. Try looking at a different date using TimeView.
Q. Why is it that when I compare the shadows in one PhotoMap with another captured on another day, they look different?
A. Please be aware that there may be slight differences between surveys due to shadow. You may see something different when in fact it’s just shadow. Depending on what time of day the survey was captured, this will affect the shadow’s direction.
Q. How precise is the PhotoMap alignment?
A. Photomaps may not be perfectly aligned in certain areas and we are working to make this as minimal as possible. You might notice this more with older surveys (pre July 2009) which were PhotoMaps flown to test and calibrate the system. We have included these older PhotoMaps as they are still of historical interest.
Q. Why do certain parts of one survey area appear to contain different colours?
A. You may notice slight colour changes in different parts of the PhotoMaps as they are captured on different days of the year and at different times of the day. Other factors such as smog and pollution will also cause such colour differences. Although we use the same camera settings for each flight, you will see from our historical data that we have deliberately tested different colour balances on our cameras to determine the best settings to maximise PhotoMap quality. Most areas are too large to be surveyed in one day and we have to fly these over numerous days. You might therefore notice slight colour differences within a survey – for example if we fly late in the afternoon and then continue the survey early the next morning.
Q. Why does a skyscraper appear slightly slanted in MultiView mode?
A. MultiView PhotoMaps are specifically designed to be used in a normal web browser, without having to download a full 3D application to view things in 3D. Because MultiView PhotoMaps are a cross between a normal overhead view and side (or oblique) views, there will be errors when there are significant changes in terrain height. Tall buildings will especially be affected and may appear slanted and not vertical. When we release a full 3D application, you will be able to see buildings, etc from all sides without these distortions.
Q. Why do certain objects disappear when you zoom in or sometimes incorrectly repeat?
A. Different photos are automatically selected to create the PhotoMaps at different scales. This is not monitored manually and therefore can unfortunately go unnoticed. This quirk is most apparent in moving objects such as cars and trains.
Q. Why do tall buildings like skyscrapers sometimes look strange?
A. Tall buildings may not be blended perfectly and therefore may not look entirely right. Try using TimeView to look at PhotoMaps from different dates instead.
Q. Why can’t I see the entire length of a train?
A. Long moving objects like trains may be cut off so you don’t see the entire length of the image. This is unusual in our PhotoMap, but unfortunately can happen.
