Kiri Engine is a free app available both for Android & iOS. It allows you to photoscan your environment and objects around you. This might not be as exciting for iOS users as iPhone has had a plethora of incredible apps that utilize the LiDAR built into the latest phones from Apple. But for us Android users this is great news, so I will be writing this from the perspective of an Android user. You can check out their website here: https://www.kiriengine.com/
Table of Contents
Free vs premium
So let me get this out of the way first, while Kiri Engine is 100% free to download, at some point, you will have to pay for exporting the models. When you first register on their app they’ll present you with a 3-question quiz, answering all questions correctly will you give three export coupons. You can get more coupons by inviting more people. They also give out a free coupon each week, so if you’re on a really tight budget you can just wait a week to get another free export.
They also have a premium version which will cost you either $10 per month or $60 for a full year, with the ability to cancel at any time. Is it worth it? It depends on your end goal, if you want to make high poly models I’d say you are better off going the DSLR + PC route, I’ve written a guide on a 100% free workflow for doing Photogrammetry with Blender. But if you’re just starting out with photogrammetry, buying a month or two in this app is definitely worth it.
The favorite section
If you click on the star icon next to the big plus icon at the bottom, you will find a list of 3d models made by Kiri Engine users. There are a bunch of models ranging from toy figures to fire hydrants and waffles (yes, real waffles). What you see on your phone is a low poly version of the final model, to get the high poly version you will need to use a coupon and export it.
I was actually surprised by how well most of the models looked, I’ve used a lot of other photogrammetry apps and the results are never on par with a PC workflow. But Kiri Engine really delivers when it comes to high-quality models, even the low poly models look really good, even if fully zoomed in.
The scanning process
By pressing the big plus icon at the bottom you are starting the scanning process, you can either upload photos from an album on your phone or take photos directly from inside the app.
If you are using the free version, the minimum amount of photos you need to take per scan is 20, while the maximum is 70. You can get quite far with 70 photos, but you should not expect that the model produced will have high-resolution textures or be high poly. To get those types of results, you’ll have to opt for the premium version which allows you to take up to 200 photos, and that is well enough to create something really good-looking.
Just like with any other photogrammetry app, you need to follow the general guidelines to get the best scan possible. Follow these tips if you want to get the best results:
- Avoid harsh light, shoot on cloudy days or use a diffuser if you’re inside
- Objects that are shiny or reflective cannot be scanned, if you still want to scan them they will need to be painted in a matte color
- Objects that have little to no surface details are very hard to scan
- Take photos from as many angles as possible, from below, middle and top
- Make sure there is overlap between all the photos
When you’ve gotten as many photos as you like, it’s time to upload the photos to Kiri Engine.
The uploading process
When you are done with the photos you’ll be prompted with the upload screen. Here you can name your object, set a label for it, toggle visibility for other users, change the file format and of course, change the model quality from low to high. There’s also a beta feature available that will mask out your object using AI, basically removing the background and just keeping the object. Do note that this is a beta feature however and might not work as intended.
When you hit the upload button you’ll start sending all the photos you took to Kiri Engines cloud server. This is where having a good internet connection will help tremendously, especially if you have taken up to 200 photos. Make sure you’re on a WiFi connection otherwise you might use up all your data. The upload takes anywhere from 5 to 20 minutes, majorly depending on the number of photos you took.
After the upload, you’ll be greeted with the processed model, with textures and everything. In this window, you can rotate and zoom on your object, this is the time to check if your model has been processed correctly. Some things, like smaller holes or uneven surfaces, can be fixed in most 3D software. But if you see large gaping holes or deformed parts, it’s better to go back and do it all over again. Make sure to follow the steps I listed above, as these will ensure the best possible quality.
To download the model to your PC, just share the link with yourself and open it up on your PC. It’s valid for one hour after creation.
I will be honest with you, I was pretty skeptical at first since I’ve tried many other photogrammetry apps for Android and they always disappoint. With Kiri Engine, however, I was pretty surprised at the amount of detail I got. I took 70 photos of a small statue in the old town area of Stockholm, I did a full 360-degree orbit and then I did some close-up shots. 70 shots is not a lot, so getting ultra-crisp textures won’t be possible using the free version sadly.
The export gives you a high poly file along with a low poly file, which is a nice time saver as you’ll be able to bake the mesh details right onto the low poly without doing any extra prep work. Checking in Blender, the high poly model had just over 1M faces, which is a lot but that is expected if you’re trying to get the most out of a photoscan.
Here’s the textured version opened up in Blender:
Distorted textures, weird geometry, it looks more like an abomination than anything else so how come I was so impressed? Well because I’m pulling your leg, at least a little, I wasn’t able to get proper photos of those parts. So let’s instead take a look at some of the parts that I actually managed to take good photos of:
The detail captured in the parts I was able to get up close on, is phenomenal. This is very comparable to my DSLR and Meshroom, which is quite crazy in my opinion. On the image above I have enabled Cavity in the viewport to further highlight all the features. You might notice that a lot of the parts are noisy and this is something you will encounter with every software out there. It’s however very easy to clean up with the Smooth brush in Sculpting Mode. And bear in mind that this is a stone statue that’s been sitting here since the mid-50s, it’s weathered and beaten up.
But it’s not all wonderful, the fact that I cannot lock my exposure when taking photos makes it hard to get a nice and evenly lit texture. I cannot find if this is dependent on your phone or not, but my phone was on full auto throughout the whole process. I could adjust the exposure by tapping on my screen, but I’m pretty sure I saw some change in exposure even then. I also think it auto-adjusted the white balance, as the model is much more yellow on one side, while the other one is more true to its real colors.
Hopefully, this will be fixed in a future update, otherwise, you can always use your own camera (instead of their app) and just upload the photos. That way you’ll have manual control over the focus, exposure, and white balance. It does bring another step into the process, as you’ll have to keep track of how many photos you took.
My final thoughts
I think the Kiri Engine app is great, it allows the normal consumer to get a taste of the power of photogrammetry. It’s very easy to use and the UI and UX are designed in a way that everyone will understand, no matter their previous knowledge. If you know what you’re doing, the end results can be fantastic and pretty much compete with the DSLR+PC workflow.
The simplicity of the app is also a drawback if you’re a more advanced user. Seeing as you have no choice of fine-tuning the actual setting, except 3 different presets, it might be difficult to get a model exactly the way you want it But then again if you’re working on big-budget projects, you are most likely also not using a smartphone to do photoscans.
All in all, a great choice if you’re doing this on a hobby level or on smaller-sized projects. I know I’ll be trying out the premium version for a month or two and see just what kind of quality I can get.