I need to take pictures of multiple trees that were planted a year earlier in some far away terrain. The pictures should give clear impression of how large each tree is. So I guess I should put some object of known size next to a tree before taking a picture. Trees are about one foot high.
What object do I use? I thought of a plastic bottle with inch point drawn with a permanent marker. That works - the bottle is easy to carry (which is good when going to a far away terrain) and stands stably without being inserted into ground (a ruler lacks this advantage). Yet it looks kind of uncool - some dull plastic bottle and it's not very clear that those are inch points so it isn't very illustrative.
What other mobile object could be used for this scenario?