Observations of the planets in our solar system cover a wide range of scales and are undertaken using a variety of techniques and platforms, resulting in extremely rich data sets. This review paper provides a basic introduction to the available range of planetary science data sets, and the combination of these data sets over a range of scales, resolutions, and techniques to address geological problems. The wealth of data available and the use of a selected combination of data sets to address geological problems are best illustrated by taking a closer look at the planet Mars. As a result of the increasing precision of spacecraft sensors, we now have data sets that cover the whole planet at spatial resolutions ranging from kilometers down to meters (e.g., Mars Global Surveyor) and multiple wavelengths (e.g., Mars Reconnaissance Orbiter), which have been collected over several years. This global coverage is complemented by surface missions that provide localized data sets down to microscopic resolutions (Mars Exploration Rovers). Thus, it is now possible to study geological features and processes quantitatively over an impressive range of scales. The combination of new data sets from current and future missions to Mars (e.g., Mars Express and Mars Reconnaissance Orbiter) will facilitate attempts to unlock the third dimension of Martian geology. The experience gained at Mars will help us to plan and exploit the 3-D exploration of other planets in the future.