Photos blurry due to slope, or for another reason?

PIX4Dcapture PIX4Dcapture Questions/Troubleshooting
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I can’t figure out how to get my images from the app on my ipad to anywhere else (see my post under “processing”), so I can’t post an example of this, but the last time I flew with this app, the drone flew the correct route, but didn’t take good pictures. I had the camera set for 90-degrees, which I believe is supposed to be straight down, but the app took pictures that showed the horizon, so I don’t know what it really did… Anyway, the pictures it took of flat ground are clear, but show the horizon. The pictures it took of the 30-40 degree slope portion, however, are extremely (and unusably) blurry. An orange traffic cone we were using for ground control just appears as one long, blurred orange line.

We tried using both fast and safety mode, and safety mode was marginally better, but still unusable. I showed the pictures to an amateur photographer, and he told me it looked like motion blur, but the drone supposedly stopped to take the picture at least during the second flight because it was using safe mode. There was very little wind, so I don’t think that was an issue.

My original instinct was that our error was that we needed to reangle the camera to take a good shot of the slope, but I’m not so sure. I don’t know what to make of the horizon appearing in the other photos. Also, I don’t know if this makes a difference, but we were flying quite high in the air–300ft or so. Since the app doesn’t adjust for terrain (to my knowledge anyway) and we could only fly from the bottom of the slope, we had to set the altitude quite high so we wouldn’t crash into the ground.

Any suggestions? I’m really tired of google searching this issue and finding nothing.

By the way, this website always gives me an obscene delay between my actual typing and the words appearing on the screen, which is unbelievably annoying. Please fix this issue!

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OK, I figured out how to post some pictures. Here’s the blurriest among them. Taken about 300ft AGL (this is AGL from where I was standing on the road, however, presumably not the highest part of the slope). Camera is supposedly pointed at 90-degrees. This was taken in Fast Mode. 

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Just to confuse me, I guess, here’s a perfectly good image. Settings are the same as above, since this was taken during the same flight. This is on lower, relatively flat ground.

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You can see from this photo that the camera no longer appears to be angled at 90, although I did nothing to alter the settings.

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This is essentially the same photo as the first one. It’s marginally less blurry, possibly because it was taken in Safe mode rather than Fast mode, but is still unusable for mapping.

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Hi Sara,

Thank you for sharing the example images so that we better understand the case.

Indeed for a 2D map of an area without significant terrain variation, performing one or multiple flights (based on the size of the area) is recommended. However, for terrain with slopes and important elevation differences images taken from the same altitude will not give good results as the ground sampling distance (GSD), or pixel size, will be very different for the parts of the image with different elevation. Additionally, the level of detail of the terrain at the different elevation levels will be significantly different.

Did you maybe notice if the blurry images are taken when the drone turns and changes grid line? We are aware that when the drone turns 90 degrees for the next pass it sometimes results in capturing blurry images.

Are all the images acquired during the same flight? Which camera did you use with the Inspire 1? Note a new DJI firmware was recently released (1.10.1.40 on 15.12.2016), so we recommend to upgrade the drone before trying Pix4Dcapture next time.
Did you set the camera angle before you perform the flight? For the images capturing the horizon, in Pix4D desktop software you can mask it by using the annotation tool. For more information you can take a look here: https://support.pix4d.com/hc/en-us/articles/202560549.

If the forum page is a bit laggy when you type in, could it be that the computer is doing a tasks quite demanding at the same time?

Regards,

7

Were you able to resolve this issue? I had the same problem today. Most of the pictures were out of focus. Flew at 200ft, overcast, no wind, over very flat terrain with one small building. I can’t use this to create any kind of map product. 

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Pix 4d support,

Based on the resulting photos from our flights, I figured that we’d need to do multiple flights with different heights and angles, but I don’t know how to factor this into our planning. Is there some kind of formula, e.g. 40-degrees slope, point the camera at 40 degrees or something? It’s very hard for me to get permission to fly in the area where I took the photo, so I was unable to do very much trial and error. Also, I would think that taking imagery from multiple heights or different angles would make it hard for Pix4DMapper and other programs to process the imagery into an orthomosaic. Am I wrong in this assumption?

I didn’t notice if the photos were taken during turns or not, but if this is indeed what occurred, how would I correct that? It seems as though this is a software issue that Pix4d should address. And what about the photo that is in focus but is clearly taken at the wrong angle? What does this mean?

The first two photos were taken on one flight set in fast mode. The second two were taken in another flight following the same route and specifications as the first, except that the camera was set to safe mode instead of fast mode. We used the camera that comes with the Inspire1 drone, and yes, it’s in focus, set to the correct settings, etc. We took other pictures with the same camera a few days later using the DJI Go app and they were perfectly fine. The upgrade had not been released when we took the photos, and I’ve been away and haven’t had a chance to upgrade yet, so I can’t say whether that will fix the problem or not. Hopefully I’ll be able to give that a try.

 

The camera angle was set to 90 for both flights. It’s good to know that you have an annotation tool, but in this circumstance it does me no good. The main sections I wanted to photograph are all in the blurry photographs. The clear photos don’t show anything much except the terrain. More importantly, however, the photos should not have captured the horizon at all. The fact that they did means that something went wrong, and I’d like to know what it is.

 

My computer is not doing anything much. It’s open to your page, and my email is open in a new tab. I tried closing the other tab, but the speed was not affected. I really think it’s your webpage. I’ve posted questions on DJI’s forum before, and I don’t have this issue. It’s honestly so frustrating that I’m typing this on Word and pasting it to your site because it’s already taken me a good half hour to type something that should have taken fifteen minutes.

 

Thanks, of course, for all of your help. Hopefully I’ll be able to fly again soon and test this again.

Sara

 

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The blurry factor has hit us too. We’re using the latest PIX4D capture build, actually up until recently we’ve used Ultimate flight as a completely manual ground station. The point is, we tried to capture in order to create just an orthomap, in an overcast day and the app went on to capture photos with 1/15 shutter speed!!!

Check how blurry the GCP appears at about the center of the image (I’ve had it cropped). We’ve ran multiple missions in the past successfully with the app, what’s wrong after the last update is really weird. I think it is not logical to allow the app to capture pics with such big exposure times! Previous projects used 1/300 speeds and ISO 100 which seems quite good

 

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@Kam

With the current Android and iOS apps, the drone does not capture image while turning. Is the blur due to motion or to the camera focus? Were you flying at the maximum speed with Pix4Dcapture? Which drone do you use?

@Sara

The dataset may consist of aerial nadir, oblique, terrestrial imagery or a combination of them. There are no limitations from that side.

When processing different types of dataset like oblique and nadir imagery together, it is recommended to process step 1 for each sub-project separately and to run steps 2 and 3 after having combined the sub-projects all together. This improves the calibration among images captured in the same conditions.

At least 3 manual tie points (MTPs) or ground control points (GCPs) should be created for each subproject in common areas that are shared between two or more datasets. Make sure they have the same name in both sub-projects so that Pix4Dmapper identifies these points as common features to link the subprojects. Some readjustments can be done after merging if needed by adding more MTPs.

Step by step procedure on how to merge sub-projects: https://support.pix4d.com/hc/en-us/articles/202558529

To optimize the image acquisition plan, we recommend to take pictures so that the camera is perpendicular to the surface/object you want to reconstruct. In other words, if you want to map a building roof, you should nadir with the camera vertical. On the other hand, if you are interested in building facades, you should fly in front of it with the camera horizontal. With Pix4Dcapture, there a double grid mission that allows to capture at the same time top and side information with a pre-defined camera angle.

For more information about the data acquisition plan, please see: https://support.pix4d.com/hc/en-us/articles/202557459

With the current Android and iOS apps, the drone does not capture image while turning.

About the problem related to our web page we are surprised since it is the first time we hear about this issue. Which browser are you using? Perhaps you could try to install another one to see if this persists?

@Dim

Which drone were you flying with the iOS app? Also was it at the maximum speed? Did you try to reduce it?

Regards,

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Hi Ms. Julie,

We’ve got blurred images also… when we flew the INSPIRE-1 with the X3 on it. The Project area was located in the mountain, so what I did was 1st: flew the drone at the bottom of the mountain with an altitude of 150m and the other mission is set at the top of the mountain and with an altitude of 100m.

what will you suggest if I have a mission with a mountain on it? or what are the best parameters for flying the drone with a higher ground?

Thank you in advance :slight_smile:

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@RASA Surveying: This article should help you for this kind of projects: https://support.pix4d.com/hc/en-us/articles/204656209
More specifically, the section Multiple flights at different constant altitudes. Note that if you have a different altitude between the ground and the drone (with the same camera) the Ground Sampling Distance (GSD) will be different. It’s recommended to have approximately the same GSD across the project. If the GSD is too different between different flights, it will be difficult for the software to match the images. That’s why it’s recommended to do several flights that fly approximately at the same altitude above the ground. 

1 Like
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Oh I see… maybe that’s the reason why I got blurred images… but is it possible that strong wind was also one of the causes from blurring of the images? although we do have a gimbal ?

By the way… THANK YOU Sir @Pierangelo for the response :slight_smile:

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@RASA Surveying: You are welcome!

Yes, it could be that the wind had an influence on the quality of the images. Wind can also have an influence on the overlap, e.g. if the wind pushes the drone it might not trigger the image at the right distance from the previous one, thereby resulting in a less good overlap. It’s the other way around if the wind slows down the drone, which could result in a higher overlap. Generally, it alternates from one line of the flight to the next.