convert - Converting TIFF file to LAS file in QGIS?

I've been asked by a client to compile LiDAR files (currently in GeoTiff format) into a LAS dataset.

Is this possible within QGIS?

I have downloaded LAStools, but I'm still fairly new to LiDAR so I'm not sure what all the tools do!

I know this is possible in ArcGIS, but I don't currently have access to the software. I see a lot of questions already asked concerning opening LAS files in QGIS, but here I am wanting to convert TIFFs into LAS format.

I don't have the raw data - I only have asc files from which I've made the GeoTiffs from.

Answer

You cannot convert geotiff to las, however, LASTools las2las allows converting ASCII (.asc) format files to las format (source). For example:

las2las -i in_data.asc -o out_data.las