After finishing the geometry of the church I am modelling in SketchUp, it was time to move on to the texturing of the object. So also for this part I tried the different options that SketchUp offers.
First I tried to use the project texture function when using the match photo feature. This allows you to align your model to a photo and will then project this photo as a texture onto your model. I guess this might work well if you have an object that is not so complex in shape, but for my church it did not work that well. Since the shape I modelled did not match the real church 100% and because some photos had some distortion as well, the texture never fit properly on the model. I think later I will try this function again with a more simple (rectangular) object, but for now it does not allow me to make textures with the quality I want.
So after that I just tried to import my photos directly as textures (without letting SketchUp projecting them). You can then map them in SketchUp quite easily by putting the pins at the corners of your faces in the photo and then aligning them with the face. This gave slightly better results than the projecting, because you have more control over where the texture goes. But still it is quite hard to align different photos correctly and let the textures continue smoothly over different faces.
So I guess in the end it sounds too good to be true that you can very easily make textures using only photos. My next attempt will be to make the texture in the normal way, by composing it manually from the photos using GIMP. I am sure that will result in the quality I am looking for, just a little more work. I will post the results again once this phase is done.