A real point of confusion for World of Tanks newcomers is the combined concepts of View Range, Radio Range, Spotting Distance and Camouflage. View Range is the physical limit to your tank’s sight – tanks outside of this range cannot be seen. Radio Range determines how far away from your tank a broadcasting or listening ally can be in order to be heard or hear you. Spotting Distance is the distance from your tank at which a moving or stationary tank will be “detected”. Camouflage impacts detection by counteracting the Spotting Distance with a modifier. Some tanks have inherent camouflage values which are better than others. Lights, for example, are generally better at camouflage, as are many Tank Destroyers.
It is important to firstly understand the difference between View Range and Spotting Distance. Just because you can see 320 meters does not mean you will notice an enemy tank that far away. Spotting Distance is always significantly less than View Range. Enemy tanks within your Spotting Distance can be detected and continually viewed. Enemy tanks within your View Range but outside of your Spotting Distance are visible for as long they are spotted by an ally within Radio Range. The most literal way to look at View Range is the range beyond which tanks will not be rendered. Even if an ally spots someone and is within Radio Range, your View Range limitations will prevent the spotted tank from being displayed outside of them. View Range and Spotting Distance are positively affected by binoculars and/or coated optics (equipment options).
Camouflage reduces an enemy tank’s Spotting Distance relative to your vehicle and vice versa. It is an inherent statistic for each tank which is further modified by factors such as camouflage paint (about a 5% increase camouflage rating), a camouflage net which is equipped (25% increase to camouflage rating), terrain features (bushes, fallen trees, etc., varying in impact), and so on. The stronger a tank’s camouflage, the shorter an enemy tank’s Spotting Distance is in relation to that tank. Camouflage rating is affected negatively by movement as well as firing your gun (the sound effectively gives away your position).
Putting it all together, suppose you are in a medium tank, proceeding across the open field of Malinovka, and an enemy tank destroyer is hunkered down behind a bush on the opposite side. Your tank has coated optics, increasing effective view range and spotting distance by 10%, slightly reduced because you are moving full speed ahead. Your camouflage rating is relatively low while in motion, so you are fairly easy to spot already. The tank destroyer is stationary, concealed behind a bush, has deployed a camouflage net and is using binoculars to observe the field ahead.
Suddenly you are given the warning that you are “Detected!” while you have not spotted any enemy tanks so far. Your medium tank, taking into account the Camouflage Rating, has entered well within the View Range of the tank destroyer and furthermore just entered its Spotting Distance. As soon as the tank destroyer spots you, any other enemy tanks within radio range of the TD and within View Range to physically see your tank now have you on their mini map and main display with a red (or purple) icon. Meanwhile you are closing in on the tank destroyer, even though you can’t see it. The tank destroyer fires at you – whether a hit, a miss, a penetration or a bounce, the tank destroyer suddenly appears ahead, because the gunfire negates the camouflage rating temporarily. Let’s assume it’s a hit and your medium is tracked.
Your reaction is to request fire on the tank destroyer, but a few seconds later it disappears from your view. That’s because the tank destroyer’s Camouflage Rating has been restored, and it is now considered outside of your Spotting Range. At the same time, the tank destroyer has also disappeared from view of any allies who are not within their Spotting Distance from the TD and were relying on your Radio Range to help them see it.
Quite likely you’ll have taken more than the one TD shot because other enemy tanks who can see you will be firing at a stationary (tracked!) target. At this point a newcomer is tempted to think that the tank destroyer’s player is somehow cheating with a hack of some kind. However, because you now know how spotting works and why tanks just disappear, you’ll curse your luck and move on, right?