Etherscan tracks all ERC-721 ( compliant tokens as per the finalized standard at with the following caveats

1. It must emit at least one ERC-721 compliant transfer event which looks something like: 

event Transfer(address indexed _from, address indexed _to, uint256 indexed _tokenId);

2. ERC-721 tokens can also contain additional metadata like images. To enable support of viewing these images on Etherscan, we will need to manually enable support for this on our end. Given the nature of images (size, loading times, potential copyright issues, etc) the option for enabling preview images will be evaluated on a case by case basis at our discretion.  This however does not affect the tracking of all ERC-721 compliant tokens as we will still show the essential information such as the sender, receiver, tokenID and date/time of the transaction.

3. To enable ERC-721 image viewing support on Etherscan we will require the following sent to :

a. Project info such as your offcial website and token icons

b. The API endpoint for retrieving the image url

c. The average duration/time required for the image to be generated on the source server after the transaction has completed (i.e 5 minute, 30, minute, 1 hour, etc)