in my special case I needed to create a custom crs for each point in the list of points in my point layer.
it does now what it should:
here is my code so far:
import processing
canvas = qgis.utils.iface.mapCanvas()
allLayers = canvas.layers()
point_layer = allLayers[0] #this is my pointlayer in my project
point_layer_dp=point_layer.dataProvider()
vlayer_crs=point_layer_dp.crs()
vertexes = []
features = point_layer.getFeatures()
for f in features:
geom = f.geometry()
point = geom.asPoint()
vertexes.append(point)
crs_src = QgsCoordinateReferenceSystem(vlayer_crs)
for i in range(0, len(vertexes)-1):
crs = QgsCoordinateReferenceSystem()
crs.createFromProj4("+proj=aeqd +lat_0=" + str(vertexes[i][1])+ " +lon_0=" + str(vertexes[i][0]) +" +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs")
#crs.saveAsUserCRS('azimuthal equidistant point' + str(i+1))
qgis.utils.iface.mapCanvas().mapRenderer().setDestinationCrs(crs)
layer = QgsVectorLayer('LineString?crs=' + crs.toWkt(), 'line'+str(i), "memory")
layer.setCrs(crs)
pr = layer.dataProvider()
line = QgsFeature()
xform = QgsCoordinateTransform(crs_src, crs)
start_point = QgsPoint(0,0)
end_point = xform.transform(QgsPoint(vertexes[i+1]))
seg = [start_point, end_point]
line.setGeometry(QgsGeometry.fromPolyline(seg))
pr.addFeatures([line])
layer.updateExtents()
QgsMapLayerRegistry.instance().addMapLayer(layer)
dens_layer = processing.runalg("qgis:densifygeometriesgivenaninterval",'line'+str(i),1000,None)
vlayer=QgsVectorLayer(dens_layer.get('OUTPUT'), "densified_layer" + str(i), "ogr")
QgsMapLayerRegistry.instance().addMapLayer(vlayer)
qgis.utils.iface.mapCanvas().mapRenderer().setDestinationCrs(crs_src)
Now it's only missing to get the densified layers into EPSG 4326 and merge them... But this is prob. another story to tell.