csv - PyQGIS export return blank .tif

I'm new to pyqgis and trying to bring up from the previous post with a little progress from the last (implemented debugging tool pdb) but now trying to export into a .tif file so that I can check on the vertices from the csv geometry. Unfortunately I get stuck with an blank render .tif image. The render.tif filesize is showing 1.9mb, when I download and view locally, the image only has the background with white colour and no vertices.

At the same time, I checked my csv file and also looping through the features of the layer after export the csv files. They are all good...

How can I have all the features from the vector layer to be shown on the .tif image file? Anyone please help? :/

PS: I'm on ubuntu server and using PyQGIS.

Tried with render.fullExtent() and render.extent(), both return blank image.tif

Inserted sample of elevp.csv

My code:-

#!/usr/bin/python
import sys
import qgis

import PyQt4

from qgis.core import *
from qgis.utils import *
from qgis.gui import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtXml import *
import pdb 



qgis_prefix="/usr"    
QgsApplication.setPrefixPath(qgis_prefix, True) 
QgsApplication.initQgis()
app = QgsApplication([], False)


uri = "/home/ubuntu/pyqgis/elevp.csv?crs=%s&delimiter=%s&xField=%s&yField=%s&elevField=%s" % ("EPSG:4326",";","x","y","elev")
vlayer = QgsVectorLayer(uri, "test", "delimitedtext")


QgsMapLayerRegistry.instance().addMapLayer(vlayer)

# create image
img = QImage(QSize(800, 600), QImage.Format_ARGB32_Premultiplied)

# set image's background color
color = QColor(255, 255, 255)
img.fill(color.rgb())

# create painter

p = QPainter()
p.begin(img)
p.setRenderHint(QPainter.Antialiasing)

render = QgsMapRenderer()

# set layer set
lst = [vlayer.id()]
print(lst)
render.setLayerSet(lst)


# set extent
rect = QgsRectangle(render.fullExtent())
rect.scale(1.1)
render.setExtent(rect)

# set output size
render.setOutputSize(img.size(), img.logicalDpiX())

# do the rendering

render.render(p)

p.end()
# save image
img.save("/home/ubuntu/pyqgis/render.tif","tif")

Sample elevp.csv:-

x;y;elev
120;960;13
360;40;52

640;840;3