Pix4d .las

[flightsurvey]

I am trying to convert a Pix4D .las file and it appears as a straight line. Does anyone know of conversion options that would address this?

Cheers

[m-schuetz]

That's likely because the coordinates are stored in lat/lon/height inside the las file. You're getting a line because lat/long are so much smaller than height. You'll need to convert your las file to another las file in a uniform cartesian coordinate system with XYZ coordinates. Not sure how to do that but maybe there is an option in Pix4D to choose another coordinate system on export.

[flightsurvey]

Ok, thanks for getting back so swiftly.

[flightsurvey]

It must be posible as the Eclepens example states that the source data is from Pix4D - http://potree.org/showcase/eclepens.html. Any chance of talking to the person who submitted it to the gallery?

[m-schuetz]

That was me, I've got the las from Pix4D already in the right coordinate system.

[vvovvo]

We had the same issue while working with the New York Post Sandy dataset. We solved it by using FME to convert the data from lat/lon the correct projected coordinate system. If you don't have FME, I guess liblas can also do the conversion (see --t_srs https://www.liblas.org/utilities/las2las.html).

On Friday, 22 December 2017, 15:20, Flight Survey Ltd <notifications@github.com> wrote:

It must be posible as the Eclepens example states that the source data is from Pix4D - http://potree.org/showcase/eclepens.html. Any chance of talking to the person who submitted it to the gallery?— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[flightsurvey]

Cheers all.

[flightsurvey]

vvovvo - I've just had a look at las2las. I don't suppose that you could help me a little bit further by telling what the parameters for the --t_srs conversion should be if you know? Cheers

[flightsurvey]

I've installed las2las according to the directions but when I run it fails saying that one or other dll could not be found. Tried any number of times to reinstall but it's not playing ball. I wonder if Windows 10 is an issue?

[vvovvo]

You can use an EPSG spatial reference ID for --t_srs. The exact SRID depends on the geo-location of your dataset.  Below is the command I used to re-project the New York Post Sandy data. Here are the screenshots of the data before and after the transformation. las2las -v 20140326_usgsnyc14_18TWK790955.las 20140326_usgsnyc14_18TWK790955_reprojected.las --offset 277000,33000,0 --scale .01 .01 .01 --a_srs EPSG:4269 --t_srs EPSG:32118 As per the liblas installation, I cannot help since I am on Linux.

On Friday, 22 December 2017, 17:37, Flight Survey Ltd <notifications@github.com> wrote:

I've installed las2las according to the directions but when I run it fails saying that one or other dll could not be found. Tried any number of times to reinstall but it's not playing ball. I wonder if Windows 10 is an issue?— You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[flightsurvey]

Hi, I'm sorry but I have only just seen this - thank you very much for getting back. I'll give it a try.

[bfreed]

I'm sure I'm too late to help flightsurvey, but for anyone else who lands here: You should set up the output coordinate system in Pix4D to be a projected coordinate system. Instructions here: https://support.pix4d.com/hc/en-us/articles/205294205-Step-2-Creating-a-Project-4-Selecting-the-Output-GCP-Coordinate-System

In the US, the State Plane Coordinate System is usually a good bet, and the search function works well. Example: Choose "Unit: ft", then check Known Coordinate System, then start typing your state name. Ex: "Penn" brings up a list for Pennsylvania. Stick with NAD83 and the appropriate part of the state. Output will work great with PotreeConverter, we do it all the time.

[flightsurvey]

It's never too late and thank you very much for getting in contact. I'll let you know how I get on. Cheers.