Why are projections necessary when using GIS?

Projections are essential when using Geographic Information Systems (GIS) because they allow for the transformation of the earth's three-dimensional surface onto a two-dimensional plane, which is crucial for accurate analysis and representation of geographic data. In this context, the correct choice relates specifically to the need for adjusting data files for flat software applications. Since GIS operates on flat surfaces such as computer screens, the geographical data must be projected accordingly to ensure spatial accuracy and maintain the relationships between different geographic elements.

Without the appropriate projection, the data could misrepresent distances, areas, and angles, leading to inaccurate conclusions. Each type of projection serves different purposes, such as retaining area, shape, or distance, which is why it’s important for GIS professionals to choose the right one based on their analytical needs.

Regarding the other options, representing three-dimensional shapes is more about 3D modeling than projections, enhancing color in satellite images pertains to image processing rather than spatial data accuracy, and creating more data layers does not directly relate to the purpose of projections in handling spatial data.