It not about html or CMS or .net website. Its about proper sitemap and robots.txt file. Actually you are right we can use different sitemap file like page URLs, Image URLs and Video URLs. But make sure that use only proper URLs not like las mod, las freq, and more that is waste of time. Use this link [url]https://support.google.com/webmasters/answer/178636?hl=en[/url] to know how to create image sitemap file.
Finally, you can use upto 50,000 URL per sitemap folder, if more than you can go with new sub-folder.