Depth sensor + LWIR registration to generate coloured pointclouds

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Hi,

I am trying to generate a colored point cloud using a depth camera and an thermal camera. I have 2 questions.

1. I am unclear on how to do external calibration to find the tf of the thermal camera wrt to depth camera. I want to do something like this http://wiki.ros.org/openni_launch/Tut... but this package isn't available for indigo. can I use camera_pose_calibration supported on indigo? or should I use industrial_extrinsic_calibration ?
2. To create a colored point cloud, i looked at depth_image_proc/point_cloud_xyzrgb which requires a rectified color image, but the thermal camera images are gray scale an i have a image_rect instead of image_rect_color. can I remap the image as image_rect_color or should i convert my gray scale image to a color image using cv::colormap().

System details:

ROS version :Indigo

Ubuntu 14.04 running on odroid

Any help regarding this is appreciated

Thanks

Akshay