The situation you're describing can get a bit complex when it comes to copyright law, but here’s a general breakdown:
Copyright of Photographs
Photographs are generally considered creative works, and as such, they are protected by copyright law. Even photos of public landmarks, like the Pyramids of Giza, can be copyrighted if taken by a photographer, because the photographer's choices (e.g., composition, lighting, timing) contribute to its creativity.
Using a Sketch or Drawing of a Photograph
If you create a sketch or drawing based on a photograph, this may still be considered a "derivative work," which means you’re transforming an existing copyrighted work into something new. However, derivative works still require permission from the original copyright holder unless the photograph is:
Public domain: Some photographs are not protected by copyright, such as very old photos, or those released explicitly into the public domain.
Fair use: In some cases, your use of the photograph might fall under "fair use" (depending on factors like the purpose of use, whether it’s transformative, and the market effect).
Incorporating It Into Other Creative Works
If the original photograph is copyrighted, creating a sketch based on it and then using that sketch in another creative project (e.g., a poster or design) may still infringe on the original copyright if you haven't transformed it enough or sought permission. However, if your sketch is highly transformative (e.g., it significantly alters the look, feel, and purpose of the original photo), it might be less likely to violate copyright.
How to Stay Safe Legally
Use photographs from the public domain or those with creative commons licenses that allow derivative works.
Get permission from the photographer if you want to directly reference their work in your drawing or sketch.
Create from your own reference material (e.g., your own photos), so there’s no risk of infringement.
For further insights into how visual elements, like sketches and graphic design, can shape brand perception and influence audiences, check out this resource on How Graphic Design Influences Brand Perception.