I am completely new to 3D and started with Jeff Lamarche’s tutorials as an introduction to openGL ES for iPhone, then so far, I am able to draw a spinning sphere, which will the base of my application.
What I want to do is render a planet Earth, thanks to 2D GIS vector data (polygones, lines or points with latitude/longitude or x/y coord).
I want to be able to turn different layers on/off and maybe able to identify an object that wold be touched.
My questions are :
would it be easier to rasterize my vector data to use them as image texture or apply the vector data onto the sphere (keeping in mind that I want to turn on/off the layers, the touch-enabled objects being optional)?
would it be easier to use a software like blender to draw the planet and add the layers rather than starting with the sphere I already have (procedural sphere)?
do the export tool from blender to opengl work well?
This kind of question is difficult to answer in general. Technically your intention sounds a lot like if you would like to write a program like Google Earth or KDE Marble. Since you’re referring to GIS data you will require very high resolution. Textures only make sense for limited resolution data.
GIS applications usually work using hybrid approaches where some vector data are rendered directly (roads, waters, borders), while others are rendered to texture and the texture, or more accurately texture tiles, being used as caches, for example for building outlines in dense cities or the like. However data as it comes from say OSM can be directly rendered as vector data, since they are not very dense.