Messages

16

General / Losing Marker Placements? Process For Second Update of GCP Marker Locations

« on: May 06, 2020, 09:02:41 PM »

I've encountered a strange issue.  I have GCP markers that the ground control markers appear in upwards of 20 photos per marker.  I loaded the marker coordinates, filtered the photos by each marker and manually centered the marker on the visible control point in the photo then unchecked the cameras, left only the markers checked, then optimized the cameras.  However, I later come to find that some of the photos are not showing the green flag indicating that I manually aligned the marker.  So I went through all the markers again.  Did some processing. Saved the project. Then when I loaded the project again, I once again found markers without the green flag!  Either there is some sort of bug, or, the only explanation would be I didn't scroll down far enough in the photo window to discover all the images.

With that being said, when I later move the markers after doing the optimization step, do I just need to run the optimization step again, or do I need to reset the camera alignment, re-align the photos, THEN run the optimization step again?

The workflow in the documentation always shows you align photos, then place markers, then optimize.  Is the advantage to doing the marker placement after alignement so that you can generate the mesh based on the sparse cloud so you can locate the photos with the markers, or if the photos are already geotagged can you place the markers before aligning the photos?  I would guess if the coords in the photos can have an error of say up to 5 meters, it may miss some of the photos with the markers in it when you use the filter by photos function?

17

General / Re: Camera Position Accuracy Setting For PPK + GCP

« on: April 28, 2020, 08:22:25 PM »

If I already did the first methos (10m camera accuracy > aligned cameras > loaded and marked GCPs > optimize with GCP only)

If I try the GCP update method with higher camera accuracy I am assuming I basically need to start from the beginning and re-align all the GCP markers, then use Update instead of Optimize?

18

General / Camera Position Accuracy Setting For PPK + GCP

« on: April 28, 2020, 09:37:29 AM »

My photos are geotagged using PPK however I did not have accurate coordinates for the position of the base station.  So relative camera position accuracy is high but absolute world coordinate position accuracy is low - typical GPS (3m horizontal, 10-20m vertical)

I also have several GCPs (I was unable to set the base station on one of them) which I have accurate coordinates for.

Theoretically I would think the PPK generated camera positions would improve relative accuracy of the ground surface between GCPs, where the GCPs would correct the absolute positional accuracy. 

I see there is a setting for camera position and marker position accuracy. My question is, in this circumstance do I leave the camera position accuracy at the default 10m because that is for absolute position accuracy, or do I change it to something like 0.1m?  I'm assuming I leave it assuming that is absolute position accuracy.  But the model should still be more accurate using PPK as the error in the GPS coordinates between photos should not fluctuate that much as compared to non PPK?

19

General / Re: False Color R+G+B GeoTiff is Dark - Altum Multispectral Camera

« on: March 09, 2020, 07:45:44 PM »

Thanks Paulo.  You have confirmed that is just how the sensor is (or the effect of the radiometric calibration.)

20

General / Are These DTM Instructions Incorrect Now?

« on: March 09, 2020, 02:34:40 AM »

https://www.agisoft.com/pdf/PS_1.1%20-Tutorial%20(IL)%20-%20Classification%20and%20DTM.pdf

This says to build a mesh then using the Export DEM function.  It looks to me like after classify the ground points, you need to use the Build DEM function not the build Mesh function in the current version of Metashape.  Is that right?

This files pops up all the time when searching for Metashape DTM generation.

21

General / Multispectral Point Cloud Export

« on: March 09, 2020, 01:58:31 AM »

How is the Point Cloud Export handled for multispectral (6-band Altum sensor)?  The dense cloud information shows 6-band yet when I import the LAS file back into Metashape it says it is 4-band?  Does the point cloud generation generate a point set for each band? What is actually being exported for the 4-bands?

22

General / Re: False Color R+G+B GeoTiff is Dark - Altum Multispectral Camera

« on: March 09, 2020, 01:04:58 AM »

Image Reflectance was properly calibrated using calibration panel values obtained from Micanses using panel serial number.  Selected Panel > Locate  Panels > Use Reflectance Panel & Sun Sensor > Okay > No Errors.

So when I divide the channel / 32768 the RGB ortho using false colors is dark (as are the greyscale images for a single channel).  If I divide the channel by 16384, the RGB Ortho Export looks much closer to the actual lighting conditions.  Still a little dark.  So I guess the main question is, is it normal for the images to be so dark if reflectance calibration was used? 

23

General / Re: Multispectral Workflow

« on: March 07, 2020, 11:07:19 PM »

I'm curious, this Micansense article regarding Atlas says it outputs a 5-layer GeoTIFF.  Does Metashape when using raster transform output multi layers, one layer for each channel formula?  So if I wanted to produce a GeoTiff with calibrated reflectance values for 5 bands, I would specify B1/32768, B2/32768, B3/32768, B4/32768, B5/32768 then select Index Values on the Ortho Export and will I get a 5-layer GeoTIFF with reflectance values for each band, one per layer? 

https://support.micasense.com/hc/en-us/articles/215460518-What-are-the-units-of-the-Atlas-GeoTIFF-output-

24

General / False Color R+G+B GeoTiff is Dark - Altum Multispectral Camera

« on: March 07, 2020, 01:19:02 AM »

Doing processing first time with Altum Multispectral Camera and have got the hang of it.  However the RGB Ortho I create by combining the 3 channels using the False Color Pallete are under exposed (dark).  If I understand correctly, the formulas are ignored when using the False Color Palette, so changing the 32678 on B1/32768 should not make a difference.  Is the only way to rectify this without reshooting the photos (not sure if I can even control Exposure on Altum) to modify them in an image editor, but then wouldn't I lose the geocoding?

25

General / Re: Multispectral Workflow

« on: March 01, 2020, 04:08:43 PM »

If the option to color the dense point cloud is checked, how is that applied for multispectral images where the source images have no color (grey scale)?

26

General / Re: Multispectral Workflow

« on: February 29, 2020, 12:37:48 AM »

Thank you so much.  My application I don't need reflectance calibration as I'm not doing comparisons over time of the same subject matter.  Just one time snapshot.  However I do want to use the sun radiance correction for possible changing light conditions during the image capture process (using Micasense Altum) Does that mean when selecting the channels in the output I specify B1/32758 or B1/65535. Just want to be sure.  While I've used Metashape a lot before, this is the first time using multispectral images so I'm getting up to speed on the terminology and what it means within the software.

27

General / Multispectral Workflow

« on: February 28, 2020, 01:19:54 AM »

Going to be processing output from a Micasense Altum sensor for the first time.  I'm not doing it to generate an NDVI map for vegetation.  All I want to do is to generate and normal RGB orthomosaic and then generate an orthomosaic one each for each of the three single remaining bands (Rededge, NIR, and IR)  I've found instructions, but the they export workflow to do this is a little unclear to me.  If I want to generate more projects like this in the future I want the color palettes to match.  For the RGB bands I want the resulting orthomosaic to use the corresponding color for the palette (Red, Green and Blue), for the single band orthomosaics, I don't want to alter the color representations and just use the native greyscale of the source images for the orthomosaic.

Thanks in advance for confirmation on the workflow.

Also, has anyone also done this using Pix4D?  It seems their cloud solution does this all for you automatically by outputting an RGB orthomosaic and then single band orthomosaics for all the bands?

28

General / Ortho GSD with Images at Different Resolutions

« on: February 11, 2020, 01:31:19 AM »

For drone imageing, If you flew say a 20-acre area at 200 feet and flew two 1-acre areas inside the 20-acre area at 100 ft will Metshapre allow an orthomosaic to be created where the 1-acre areas have higher resolution than the other areas?

29

General / Has Processing Slowed Down?

« on: July 11, 2019, 12:09:21 AM »

I don't use Metashape that often but I could swear processing is taking longer these days.  Have the default settings and or processing method changed in recent versions resulting in slower processing? Especially on the textured mesh building process.

30

General / WGS84 Orthomosaic Distorted in QGIS

« on: June 04, 2019, 11:29:52 PM »

Source photos were WGS84 projection and used that projection throughout processing all the way to orth export.  When I load the GeoTIFF into QGIS the image is distorted to look wider than it should look (circles are not circular but slightly oval).  I swear I remember running into this before and I ended up trying some other projection settings in QGIS.  By changing it to NAD83 (UTM Zone 10T) it fixes it.  This seems odd this happens as the GeoTIFF looks fine through an image viewer.