Development After shelving a multi-cast project featuring
Karthi and
Dulquer Salmaan in the lead roles during December 2015, it was reported in the media that
Mani Ratnam would instead work on a new film retaining Karthi as the lead actor and
A. R. Rahman as the music composer and Ravi Varman as cinematographer. In February 2016, Karthi confirmed that he had signed on to play the lead role and would collaborate with the director twelve years after having worked with him as an assistant during the making of
Aayutha Ezhuthu (2004). Mani Ratnam requested Karthi to lose weight through the
CrossFit program and learn the basics of flying to portray the lead character of a pilot. The start of the film was delayed as the team wanted to wait for a better climate, before beginning the shoot in
Kashmir, while the team also chose to wait for Karthi to finish his commitments for the production of
Kaashmora (2016).
Sai Pallavi successfully auditioned for the leading female role of a doctor in the project and was signed on to make her debut as a lead actress in the Tamil film industry through the project. However, in April 2016, Mani Ratnam felt that the character had to be older and opted to leave Sai Pallavi out of the project, later replacing her with
Aditi Rao Hydari. Hydari participated in Tamil lessons prior to the film's shoot, in order to improve her understanding of the script. She also worked in a hospital for a few days in order to get a better understanding of her role as a doctor. Mani Ratnam and his team began location hunting in April 2016 to seek out replacements to resemble
Kashmir and scouted areas including Himachal Pradesh, Kerala, Kodaikanal, Ooty and Coonoor. Meanwhile, Mani Ratnam also worked closely with music composer A. R. Rahman and lyricist
Vairamuthu in finalizing seven songs for the film during the pre-production period. The rights to Faith Johnson's book
Four Miles to Freedom was also bought by the team, as they looked to draw inspiration from the real-life incidents of Dilip Parulkar's escape from a Pakistani jail in 1971. Actors
RJ Balaji and
Delhi Ganesh joined the cast of the film in July 2016, while actress Shraddha Srinath revealed that she would feature in a small role as a brigadier's daughter. Kannada actor
Harish Raj and Hindi actor
Vipin Sharma also joined the first schedule of the film, making their debuts in the Tamil film industry. Likewise, actresses
Lalitha and
Rukmini Vijayakumar were signed up for roles during the film's initial schedule. The film's first look poster was revealed in early July 2016, with the title of
Kaatru Veliyidai, inspired by a poem by
Subramania Bharati, officially announced.
Filming The shoot of the film began in early July 2016 in
Nilgiris,
Ooty with a twenty-day schedule featuring Karthi and Aditi Rao Hydari. The location was chosen to show
Kashmir on screen, as the latter's climate had made conducting shooting there difficult. Art director Amaran and production designer
Sharmishta Roy worked together on designing the set during the first schedule, choosing to enhance existing backgrounds rather than to create lavish sets. The team regularly shot scenes from sunrise onwards, in order to ensure that the film progressed quickly. A second schedule for the film took place in
Hyderabad during October 2016, lasting a period of ten days. The team then moved to
Leh and the surrounding areas of
Ladakh for a third schedule lasting fifteen days, with action sequences choreographed by Sham Kaushal being filmed. In late November 2016, the team moved to shoot scenes in,
Siberia and the surrounding snow-capped mountainous regions after they were denied permission to shoot action sequences involving aircraft in North India. During the ten-day schedule, the team also shot a romantic song in the snowy backdrop choreographed by
Brindha. The shoot was concluded in mid-January 2017, with the team announcing that the post-production phase would take a couple of months. ==Music==