A lighting plan generator configured to generate a lighting plan comprising a map of locations of a plurality of light units located on a ceiling of an interior space, the lighting plan generator being configured to generate the lighting plan from overlapping images captured by a mobile device from different locations as the mobile device moves through the interior space. The lighting plan generator comprises: an input configured to receive at least two images, the at least two images comprising at least partially overlapping areas; an image rectifier (160) configured to rectify the at least two images; an image data combiner (406) configured to combine data from the rectified at least two images, wherein a lighting plan (413, 415) is generated from the combined data from the rectified at least two images.