Kanye West has surprised his wife Kim Kardashian with a hologram of her late father for her 40th birthday.

The reality star posted a recording of the hologram of Robert Kardashian, who died in 2003.

"For my birthday, Kanye got me the most thoughtful gift of a lifetime," she wrote in the caption.

The video shows Robert Kardashian apparently telling his daughter he watches over her every day, as well as making jokes and dancing.

He is also seen telling Kim she married "the most, most, most, most, most genius man in the whole world".

She described the hologram as "so lifelike" and "a special surprise from heaven".

For my birthday, Kanye got me the most thoughtful gift of a lifetime. A special surprise from heaven. A hologram of my dad. ✨🤍 It is so lifelike! We watched it over and over, filled with emotion. pic.twitter.com/jD6pHo17KC

— Kim Kardashian West (@KimKardashian) October 29, 2020

Lawyer Robert Kardashian was known for defending OJ Simpson at his infamous murder trial in the 1990s. He was played by Friends star David Schwimmer in the 2016 TV dramatisation The People v OJ Simpson.

In the hologram, he can be seen saying: "Happy birthday Kimberly. Look at you, you're 40 and all grown up.

"You look beautiful just like when you were a little girl. I watch over you and your sisters and brothers and the kids every day."

From beyond the grave, he goes on to tell his daughter: "The most beautiful thing that I have witnessed is watching you grow your family...

"You are the most, most, most, most amazing mother to your four beautiful children, and they are perfect.

"Keep doing what you're doing, Kimberley. You are a beautiful soul. Know that I am very proud of you and I'm always with you. I have built a firewall around our family."

Kim and Kanye married in May 2014 and have four children together.

In her accompanying caption, Kim, who was 22 when her father died, wrote: "It is so lifelike and we watched it over and over, filled with lots so tears and emotion.

"I can't even describe what this meant to me and my sisters, my brother, my mom and closest friends to experience together. Thank you so much Kanye for this memory that will last a lifetime."

Earlier this week, the reality TV star was mocked on social media for revealing she had taken her family to a private island for her birthday.

Keeping Up With The Kardashians, the show which propelled her to worldwide fame is due to end next year after 20 series.

Several social media users began making fun of the hologram after Kim posted the video.

"I see Kim has upped the relatability since the private island tweet," joked comedian David Baddiel..

Journalist Caitlin Moran noted: "I feel there's there's a giveaway moment where you can tell Kanye wrote the script for Kim's dead dad's hologram: 'Kimberley, you are married to the most, most, most, most, most, most, most genius man in the world.'"

The hologram was disappointing news for TV comedy writer Jenny Jaffe, who said: "I was gonna get Robert Kardashian holograms for my family for the holidays but now it won't be a surprise."

But many applauded Kanye for the gesture.

Metro's US entertainment reporter Nola Ojomu said: "Went to bed last night knowing everyone would go on about how 'weird' this is. But those who've followed the Kardashians properly all these years know why this gift is actually super sweet and thoughtful.

"You might not like it, but Kim and her family were always gonna love it!"

YouTuber Jenny Nicholson added: "The Kardashian hologram is ghoulish and awful but they say it's the thought that counts, and I do believe that Kanye's first thought was to raise her father from the dead and that if the tech was there he would pay to do that for her birthday."

How does the hologram work?

It is not clear what kind of technology was used. Kanye may have used a Victorian-era trick called Pepper's Ghost, where a semi-transparent mirror on a stage is used to reflect a film beamed from a projector.

That means it is actually a 2D image displayed on a screen, which itself is invisible to the audience.

Using such technology creates a relatively simple optical illusion - and is used in theatres, museums and theme park attractions such as Disney World's Haunted Mansion.

The Pepper's Ghost technique was used to create Tupac Shakur's performance at the Coachella festival in 2012, at an estimated cost of between $100,000 and $400,000 (£77,000-£308,000).

Alternatively, Kanye may have commissioned an actual hologram - which would have been considerably more expensive. It's also unclear how Robert Kardashian has been voiced.

Technology is increasingly being used to resurrect the dead on stage and screen, but not everyone supports the idea.

A hologram of Whitney Houston toured the UK earlier this year, but the experience received poor reviews.

Plans to feature a CGI version of long-dead actor James Dean in a new film were met with scorn by Hollywood stars such as Chris Evans when they were announced last year.