I am working on a map based system for a control centre. The operatives who work in the control centre work on various map based events such as traffic, roadworks etc.
One of the tasks the users wish to perform is the re-locating of events, should they move for whatever reason. There are a number of ways we can allow users to re-plot icons on the map:
Drag and drop
This is the functionality used to pan the map, therefore if it is to be replaced functionally when selecting an item we are presented with 2 problems: 1) What if the new area (where the operative would like to place the event icon) is out of scope and the may needs to be panned? 2) If the map is densely packed with draggable icons could users make the mistake of moving an icon rather than panning?
Right click to select, click to place
Problem 1 is that we've got a contextual menu for right click, not a problem because re-place icon can be an option of that, so that's issue 1 avoided. The problem I feel here is that this isn't intuitive enough, and what if the operator forgets they have the item selected and continues to use the map normally, placing the event wherever they next click?
Right click to select (via contextual menu) and left click to place with a visual aid
This idea sort of replicates google maps' streetview dropper. You right click the icon for the event, chose "re-place event" and your cursor is then followed by the icon indicating you're ready to place with a left click. My only worry about this is that the user may not know how to 'escape' the move if it's an accident, even if it it paired with a key command to cancel.
Click and drag with visual aid
Copies google maps' streetview dropper more than option 3, with the click and drag functionality of option 1. This time we would allow the map to pan with the cursor meaning if the scope was only slightly out the operative could pan to the right place.
TLDR: What is the best way for users to do this in terms of intuitiveness and what is least likely to cause mistakes? The users will be trained to intuitiveness should come second to ease-of-use.