Size and weight is a big decision factor when you are trying to find the ideal camera for your needs.
In this section, We are going to illustrate Nikon D7000 and Sigma DP3 Merrill side-by-side from the front, back and top in their relative dimensions. Nikon D7000 has external dimensions of 132 x 105 x 77 mm (5.2 x 4.13 x 3.03″) and weighs 780 g (1.72 lb / 27.51 oz) (including batteries). Sigma DP3 Merrill has external dimensions of 122 x 67 x 59 mm (4.8 x 2.64 x 2.32″) and weighs 330 g (0.73 lb / 11.64 oz) (including batteries).
Below you can see the front view size comparison of Nikon D7000 and Sigma DP3 Merrill. Sigma DP3 Merrill is 10mm narrower and 38mm shorter than Nikon D7000 but it is also 7mm thicker. As you can tell, actually this is not a fair size comparison since Sigma DP3 Merrill has a built-in lens but Nikon D7000 doesn't. Once you put a lens on D7000, its thickness will increase significantly.
Now lets look at the top view comparison of Nikon D7000 and Sigma DP3 Merrill.
Weight is another important factor especially when deciding on a camera that you want to carry with you all day.
Sigma DP3 Merrill is significantly lighter (450g ) than the Nikon D7000 which may become a big advantage especially on long walking trips.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on D7000, the total kit will weigh much higher.
With its weather sealed body, we believe that D7000 has a big advantage over DP3 Merrill which doesn't provide any kind of environmental sealing.
LCD Screen Size and Features
Nikon D7000 and Sigma DP3 Merrill's LCD screens has the same diagonal size of 3".
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.