@jonahevans made a video about how to photograph animal tracks. It is available here https://www.youtube.com/watch?v=HaLMQ2H6_PE.

You don't always need shade if sunlight comes in at an angle and the track is in full sunlight.

See https://www.bear-tracker.com/caninevsfeline.html

Feline tracks have a trapezoidal shaped pad with three lobes at the posterior of the pad and sometimes register two lobes at the anterior of the pad. The pad in feline tracks is proportionately larger than it is in canine tracks. The pad area of a canine front track is triangular. The pad area of a canine hind track can be triangular or even round in some species. The pad area of a canine track is not trapezoidal unless the animal slipped forward in mud.

The toe arrangement in feline tracks is asymmetrical and there is a leading toe - toe number 3. The toes in feline tracks are also somewhat tear drop shaped. The toe arrangement in canine tracks is symmetrical and the middle toes are more oval shaped than they are in feline tracks.

If you imagine lines being drawn between each of the pairs of side and middle toes it will form and "X". The lines of the "X" do not bisect the pad in canine tracks but they do bisect the pad in feline tracks.

Finally, felids have to expend energy to extend their claws so their claws typically do not register in their tracks. Canid claws are always extended and often register in their tracks.

Canine examples
https://www.inaturalist.org/observations/18997094 - Coyote Front on the left and hind on the right.
https://www.inaturalist.org/observations/17591110 - Domestic Dog
https://www.inaturalist.org/observations/16578205 - Domestic Dog that had slipped forward in mud so that the pad area is trapezoidal.
https://www.inaturalist.org/observations/19106805 - Gray Fox

Feline examples
https://www.inaturalist.org/observations/19106785 - Mountain Lion
https://www.inaturalist.org/observations/18636765 - Bobcat, mud
https://www.inaturalist.org/observations/17591112 - Bobcat, dry substrate
https://www.inaturalist.org/observations/19176947 - Domestic Cat

Additional Resources

This requires that the viewer know the size of the scale beforehand.

The size of the dimension, D is given by D = S * M/U.

Example: Suppose you photograph a Bobcat track and with a coin such as a quarter near the track. Also suppose that you display the photo on your computer monitor and you measure the length of the track as displayed on the monitor as being 65mm (this is M). Next, suppose that you measure the diameter of the quarter as being 28mm (this is U). Next, suppose you either measure the diameter of an actual quarter or you do a web search and determine that a quarter is 0.955" in diameter (this is S).

The length of the track, D, is 0.955" * 65mm/28mm = 2.31".