Messages

16

General / Re: Exported Orthophoto missing 90% of Pixels despite excellent Allignment.

« on: October 30, 2017, 08:31:30 PM »

Reimporting the GCP Location data and swapping the Easting (X coordinate) and Northing (Y coordinate) columns seems to have worked. This also explains why the model was upside down when opened!

 

17

General / Re: Exported Orthophoto missing 90% of Pixels despite excellent Allignment.

« on: October 30, 2017, 07:56:31 PM »

Where is the Ortho view tab? - I can't attach them, as the files are too large.
Thanks for all your help, March.

18

General / Exported Orthophoto missing 90% of Pixels despite excellent Allignment.

« on: October 30, 2017, 07:25:54 PM »

Hello,
I am attempting to export an Orthophoto using data from a Optris PI 450 Thermal Camera. The project consists of 204 Images with 12 GCPs. The Images alligned successfully with very little GCP error and the view in the model workspace appears to be good.

But when I export the orthophoto as a TIF I get a severly distorted image with 95% of the pixels missing.
Can anyone shed any light on any settings I can alter the correct this? Due to small size of the images this project can easily be processed in a short time, so feel free to look at the other project files.

Thanks, March Castle.

19

General / Lowest settings needed for Dense Point Cloud to get a precise Orthophoto?

« on: January 16, 2017, 03:17:40 PM »

My work consists of two workflows:

One is to extract crop height data from Dense point cloud data using out of camera Jpegs.

The other is to use the orthophoto to extract purely visual data using minimally processed RAW files- so that crop colour and NDVI can be properly calculated.

I am working with approx 700 images, each are 130mb Raw files - looking for 1cm/Pixel resolution.

If I want to generate an orthophoto from these RAW files to create a purely top-down 2D Image, would it decrease the accuracy of the orthophoto if I use the absolute minimum settings for Dense Point Cloud generation?

The motivation for this is that I want to cut down the processing time - I would like to skip this step entirely but it seems that generating a point cloud is a necessary step even if you are only interested in a top-down two dimensional image.

I understand that some height data is necessary even for a a flat image, as the land and crop itself is not flat, but is enough data gathered during the alignment / sparse cloud generation steps that only a minimal point cloud will be sufficient to retain our current 1cm/pixel resolution?

Thanks for your help, and forgive any ignorance on my part! March Castle.

20

General / Gap in Alignment of Orthophoto.

« on: February 08, 2016, 01:07:21 PM »

Hello,

I am having problems eliminating a gap in my Orthophoto - I have repeated the alignment several times using different settings. This example requires the alignment of 681 images using High accuracy, Disabled Pairs with a 40,000 Key point limit and a 10,000 Tie point Limit. Are these settings suitable?

I calculated the flight to include the recommended amount of overlap and the GCP Locations are accurate to within 2cm accuracy.

The images appear in the photos pane but they do not appear in the model view after the alignment process - see screenshot below. The missing images do not appear to have any more blur or distortion than any of the others in the set.

I have attached the Log if that helps.

Has anyone got any suggestions?
Thanks, March.

21

General / Re: Dense Point Cloud option not available in Build 'Mesh' dialogue box

« on: January 18, 2016, 02:50:32 PM »

Here's a screenshot. It is in 'Point cloud' view because the 'Dense Cloud' view icon is greyed out. I am unsure why as I am sure I had previously generated the Dense Point Cloud.

22

General / Re: Dense Point Cloud option not available in Build 'Mesh' dialogue box

« on: January 18, 2016, 02:00:02 PM »

Thanks for your reply Tornado, but I do not have a problem creating the LAS file - The issue I am having is when I create a Dense Point Cloud using 'Medium' settings' (which was recommended) When I export the points in the form of an LAS File, the File size is tiny (less than a Mb) and does not work when I import it into ARCGIS. When I create the Dense Point Cloud using 'High' Settings, the LAS file is much larger (around 3Gb) and can be used successfully in ARCGIS.

What makes me suspicious that is that the Dense point cloud option is unavailable in the 'Source Data' Dropdown when I proceed to the 'Build Mesh' dialogue box - only Sparse cloud data can be selected. But when I create a point cloud using 'High' settings, the Dense point cloud option is available in the 'Source Data' Dropdown within the 'Build Mesh' dialogue box.

Is there an option I am selecting in my workflow (details below) that is causing this?

I open projects containing around 500 photographs with around 80% overlap.
I then Align the photographs using the 'High' accuracy setting (all other settings are left as default)
I then assign coordinates to the GCPs
I then create a Dense Point Cloud using 'Medium' setting and 'Mild' Depth Filtering
I then create a mesh - but only Sparse cloud option is available if I have used Medium setting in dense point cloud creation.
I then Save the Orthophoto and LAS Files so that I can work with them in ARCMAP.

I am keen to avoid using 'High' settings due to the increased processing time.

23

General / Dense Point Cloud option not available in Build 'Mesh' dialogue box

« on: January 15, 2016, 06:43:25 PM »

The Dense Point Cloud option is not available in the 'Source Data' Dropdown within the 'Build Mesh' dialogue box (example attached - although this is not mine) - I can only select 'Sparse Cloud' Can anyone tell me why this is?

I am not entirely sure what defines a Sparse or Dense Point cloud.

The aim is to save the data as a LAS file so that it can be used in ARCGIS.

I have aligned the images (around 500) using High accuracy settings and the Point Cloud was generated using Medium settings using Mild depth filtering.

Thank you for your help, March Castle.

24

General / Severely Flattened Orthophoto

« on: December 03, 2015, 03:05:41 PM »

Hello,

I am having problems creating Orthophotos - they are coming out severely flattened. I have managed to get good results with these images in the past and I don't think I have changed any of the default settings I used then.

I have aligned the images successfully and I know the GCP GPS data is accurate to within 2cm.
The Co-Ordinates system I am using is OSGB 1936 / British National Grid (EPSG:27700) - But I have tried with WGS84 and I get the same results.

Thank you for your help, March Castle.