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ODE dSpaceCollide vs dCollide for 2 geom scene

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Hello there! I've spent the past few days messing around with ODE, getting a heightfield / capsule collision detection working. I have a simple scenario with just 2 geoms, the capsule and the heightfield. For some reason, if I call dCollide with the 2 geoms every physics step, I get a more or less stable simulation. However, if I use dSpaceCollide, leaving everything else the EXACT same, I get my character wildly bouncing around. I am using a fixed time step (atleast, I'm doing this:)
accumulatedTime += dt; // add the time the current frame took (t-t0)

	// do as many steps as required (maybe even 0)
	while (accumulatedTime > stepSize) {
		dSpaceCollide(space, NULL, &nearCallback);
		dWorldQuickStep(world, stepSize);

		accumulatedTime -= stepSize;

Does anyone know how to tackle such a problem? I'm thinking that dSpaceCollide is not calling dCollide on my object aptly enough, resulting in large penetration depths and equally large rebound forces. - How do you bound these rebound forces? - or ideally make it "move" the capsule to handle collisions, instead of using dynamics and forces. Here's my nearCallback (almost identical to the ODE manual):
void nearCallback(void* data, dGeomID o1, dGeomID o2) {
	if (dGeomIsSpace(o1) || dGeomIsSpace(o2)) { 

		// colliding a space with something :
		dSpaceCollide2(o1, o2, data, &nearCallback); 

		// collide all geoms internal to the space(s)
		if (dGeomIsSpace(o1))
				dSpaceCollide((dSpaceID) o1, data, &nearCallback);
		if (dGeomIsSpace(o2))
				dSpaceCollide((dSpaceID) o2, data, &nearCallback);
	} else {
		if (o1 == o2) return;

		dContact contacts[Physics::MAX_CONTACTS];

		for (int i=0; i<Physics::MAX_CONTACTS; ++i) {
			contacts.surface.mode = dContactBounce;
			contacts.surface.mu = 0;
			contacts.surface.bounce = 0;

		int numContacts = dCollide(o1, o2, Physics::MAX_CONTACTS, &contacts[0].geom, sizeof(dContact));

		for (int i=0; i < numContacts; ++i) {
			dJointID c = dJointCreateContact(Physics::world, Physics::contactGroup, &contacts);
			dJointAttach(c, dGeomGetBody(o1), dGeomGetBody(o2));

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